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Medical Policy

Policy Num:       05.001.011
Policy Name:     Acute and Maintenance Tocolysis
Policy ID:          [05.001.011]   [Ar / B /  M+ / P- ]  [5.01.07]                                                                                    

Last Review:       August 07, 2019                                                                                                                                                                   
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Related Policies:

04.001.012 Progesterone Therapy as a Technique to Reduce Preterm Birth in High-Risk Pregnancies

Acute and Maintenance Tocolysis

Summary

Tocolysis refers to the suppression of preterm labor to delay delivery. A variety of medications are used as tocolytic agents, although none are currently approved by the U.S. Food and Drug Administration for the purpose of suppressing labor. These medications have also been evaluated as maintenance therapy following successful tocolysis.

For individuals who have preterm labor or threatened preterm labor who receive acute tocolytic therapy, the evidence includes multiple randomized controlled trials and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Overall, the body of evidence has shown that the commonly used tocolytic agents presented herein are effective at inducing tocolysis in patients with preterm labor or threatened preterm labor. Data have suggested that oral terbutaline is associated with more adverse events than parenteral terbutaline for acute tocolysis. Each medication has a different risk-benefit profile, and there is no clear first-line tocolytic agent. The evidence is sufficient to determine that the technology results in a meaningful improvement in the net health outcome.

For individuals who have successful acute tocolysis for preterm labor who receive maintenance tocolytic therapy, the evidence includes randomized controlled trials and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Studies have generally not found that maintenance tocolysis lowers the rate of preterm birth or perinatal mortality, or increases the birth weight. The evidence is insufficient to determine the effects of the technology on health outcomes.

Objective

The objectives of this evidence review are to determine whether (a) acute or (b) maintenance tocolytic therapy improves the net health outcome in individuals (a) who have or are at risk of preterm labor or (b) who have had successful tocolytic therapy.

Policy Statements

Acute tocolytic therapy with calcium channel blockers, magnesium sulfate, prostaglandin inhibitors, and parenteral terbutaline may be considered medically necessary to induce tocolysis in patients with preterm (<37 weeks of gestational age) labor.

Maintenance (beyond 48-72 hours) tocolytic therapy with any medication is considered investigational.

Policy Guidelines

Patient selection criteria for induction of tocolysis include regular uterine contractions associated with cervical changes. Induction of tocolysis typically requires hospitalization to monitor for incipient delivery.

Benefit Application

BlueCard/National Account Issues

Continuous infusion of terbutaline for maintenance therapy via a subcutaneous pump (HCPCS code E0781) may be offered as part of the management protocols of high-risk pregnancies offered by carveout networks. However, as noted earlier, this therapy is considered investigational.

Benefits are determined by the group contract, member benefit booklet, and/or individual subscriber certificate in effect at the time services were rendered.  Benefit products or negotiated coverages may have all or some of the services discussed in this medical policy excluded from their coverage.

Background

TOCOLYSIS

General indications for tocolysis, or the suppression of preterm labor, include continued regular uterine contractions associated with cervical changes in a pregnant woman at less than 37 weeks of gestation. Successful delay of preterm delivery allows further fetal development and precludes potential complications of preterm delivery, especially neonatal respiratory distress syndrome. Even short-term delay of delivery is thought to be beneficial in that it allows treatment of the patient with corticosteroids, which has proved beneficial in ameliorating the effects of neonatal respiratory distress syndrome. In some cases, a short delay in delivery may also allow transport of the pregnant woman to a medical center better equipped to handle premature delivery and neonatal intensive care.

Treatment

Several agents have been used for tocolysis. The only tocolytic drug approved by the U.S. Food and Drug Administration (FDA) has been ritodrine, a beta-sympathomimetic. Ritodrine is no longer available in the United States, and thus only off-label medications are available. Terbutaline sulfate, FDA-approved for several nontocolytic indications, is also a beta-sympathomimetic. Terbutaline is available as an oral or intravenous medication and has been administered by continuous subcutaneous infusion via a portable pump for maintenance tocolysis. Other tocolytic drugs include calcium channel blockers (eg, nifedipine), magnesium sulfate, oxytocin receptor antagonists (eg, atosiban), prostaglandin inhibitors (eg, indomethacin), and nitrates (eg, nitroglycerin).

Tocolytic agents have potential to increase the risk of adverse events. The 2012 guidelines (reaffirmed 2014) issued by the American College of Obstetricians and Gynecologists summarized the potential adverse events of common classes of tocolytic agents: calcium channel blockers, nonsteroidal antiinflammatory drugs, -adrenergic receptor agonists, and magnesium sulfate.¹

Calcium Channel Blockers

• Maternal side effects: dizziness, flushing, and hypotension; suppression of heart rate, contractility, and left ventricular systolic pressure when used with magnesium sulfate; and elevation of hepatic transaminases 
• Fetal or newborn adverse events: no known adverse events

Nonsteroidal Anti-inflammatory Drugs

• Maternal side effects: nausea, esophageal reflux, gastritis, and emesis; platelet dysfunction is rarely of clinical significance in patients without underlying bleeding disorder 
• Fetal or newborn adverse events: in utero constriction of ductus arteriosus, a oligohydramnios, a necrotizing enterocolitis in preterm newborns, and patent ductus arteriosus in newborn 

a Greatest risk associated with use for more than 48 hours.

b Data are conflicting on this association.

Beta-Adrenergic Receptor Agonists 

• Maternal side effects: tachycardia, hypotension, tremor, palpitations, shortness of breath, chest discomfort, pulmonary edema, hypokalemia, and hyperglycemia 
• Fetal or newborn adverse events: fetal tachycardia

Magnesium Sulfate 

• Maternal side effects: flushing, diaphoresis, nausea, loss of deep tendon reflexes, respiratory depression, and cardiac arrest; suppression of heart rate, contractility and left ventricular systolic pressure when used with calcium channel blockers; and produces neuromuscular blockade when used with calcium channel blockers 
• Fetal or newborn adverse events: neonatal depression (note: the use of magnesium sulfate in doses and duration for fetal neuroprotection alone does not appear to be associated with an increased risk of neonatal depression when correlated with cord blood magnesium levels)

Risks Associated With Terbutaline

An FDA-conducted search of its Adverse Event Reporting System identified reports of 16 maternal deaths associated with terbutaline between 1976 and 2009.2 FDA documents indicate that, in 3 cases, it was specified that terbutaline was administered by a subcutaneous pump; and in 9 cases oral terbutaline was used instead of or in addition to injectable or subcutaneous terbutaline (presumably, in the remaining cases, the mode of administration was not reported). Moreover, between 1998 and July 2009, 12 cases of serious maternal cardiovascular events associated with terbutaline were submitted to the Adverse Event Reporting System; in 3 cases, subcutaneous terbutaline was specified and, in 5 cases, oral terbutaline was used alone or in addition to subcutaneous terbutaline.

An editorial by Rodier et al (2011) examined the human and animal evidence on risks of autism spectrum disorders associated with terbutaline.3 The commentators concluded that the literature did not support the hypothesis that 2-adrenergic agonists (including terbutaline) are associated with autism spectrum disorders in offspring.

Regulatory Status

FDA approved ritodrine for use as a tocolytic agent. Ritodrine was voluntarily withdrawn from the U.S. market in 1998.

Terbutaline has been approved by FDA for the prevention and treatment of bronchospasm in patients with asthma and reversible bronchospasm associated with bronchitis and emphysema. Like other tocolytic agents, its use for tocolysis is off-label. In response to a 2008 citizen petition, FDA reviewed safety data on terbutaline sulfate. FDA issued a safety announcement on 2011.2 Based on animal studies, FDA reclassified terbutaline from pregnancy risk category B to pregnancy risk category C. In addition, FDA required a boxed warning stating that injectable terbutaline should not be used for prevention or prolonged (beyond 2 to 3 days) treatment of preterm labor, and oral terbutaline should not be used for acute or maintenance tocolysis. The labeling change was based on a review of postmarketing safety reports submitted to the FDA’s Adverse Event Reporting System of maternal death and serious maternal cardiovascular events associated with the use of terbutaline.

Rationale

The evidence review was created in November 1997 and has been updated regularly with searches of the MEDLINE database. The most recent literature update was performed through June 4, 2018.

Evidence reviews assess the clinical evidence to determine whether the use of a technology improves the net health outcome. Broadly defined, health outcomes are length of life, quality of life, and ability to functionincluding benefits and harms. Every clinical condition has specific outcomes that are important to patients and to managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of a technology, 2 domains are examined: the relevance and the quality and credibility. To be relevant, studies must represent one or more intended clinical use of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial (RCT) is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. RCTs are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Promotion of greater diversity and inclusion in clinical research of historically marginalized groups (e.g., People of Color [African-American, Asian, Black, Latino and Native American]; LGBTQIA (Lesbian, Gay, Bisexual, Transgender, Queer, Intersex, Asexual); Women; and People with Disabilities [Physical and Invisible]) allows policy populations to be more reflective of and findings more applicable to our diverse members. While we also strive to use inclusive language related to these groups in our policies, use of gender-specific nouns (e.g., women, men, sisters, etc.) will continue when reflective of language used in publications describing study populations.

Population Reference No. 1 Policy Statement

ACUTE TOCOLYSIS

Clinical Context and Therapy Purpose

The purpose of acute tocolysis in patients who have preterm labor dis to provide a treatment option that is an alternative to or an improvement on existing therapies.

The question addressed in this evidence review is: Does acute tocolysis improve the net health outcome in women with or at risk of preterm labor?

The following PICOTS were used to select literature to inform this review.

Patients

The relevant population of interest is women experiencing or at risk of preterm labor.

Interventions

The therapy being considered is acute tocolysis. Tocolytic medications include terbutaline sulfate, calcium channel blockers (eg, nifedipine), magnesium sulfate, oxytocin receptor antagonists (eg, atosiban), prostaglandin inhibitors (eg, indomethacin), and nitrates (eg, nitroglycerin)

Comparators

The following practice is currently being used to make decisions about reducing or mitigating the risk and harms of preterm labor: no tocolytic therapy.

Outcomes

The outcomes of interest are the gestational age at birth, morbidity and mortality of the infant, and adverse events of treatment on the mother.

Timing

The timing of therapy is the 24- to 72-hour period during which tocolysis occurs and the gestational age in weeks.

Setting

Therapy is administered in an inpatient care setting by a specialist (eg, obstetrician-gynecologist).

Systematic Reviews

Studies have focused on whether tocolytic agents prevent preterm delivery and thereby reduce associated maternal and neonatal risks. Numerous RCTs on acute tocolysis have been published and Haas et al (2009) conducted a comprehensive systematic review and meta-analysis of RCTs. 4 They included 58 studies that directly compared different tocolytic medications or compared 1 medication with placebo or usual care. Studies were selected if they compared 2 drugs in the same class but excluded if they included 2 doses of the same medication. Participants were women diagnosed with preterm labor or threatened preterm labor. The analysis was limited to studies with fetuses of mean gestational ages between 28 weeks and 32 weeks of gestation. Multiple gestations was not an exclusion criterion—but if trials stratified on this variable, only data on singleton pregnancies were used. Data were extracted for each outcome and combined by drug class to calculate a weighted mean and standard error for proportions of successful events; proportions were weighted based on the number of participants in each study. Primary efficacy and safety outcomes are as follows in Tables 1 and 2.

Table 1. Effect of Tocolytics on Delaying Birth (Weighted Percentage of Women Experiencing Outcome)

Adapted from Haas et al (2009).⁴

CI: confidence interval.

Table 2. Adverse Maternal and Neonatal Events Associated With Tocolytics (Weighted Percentage
of Women/Neonates Experiencing Outcome)

Adapted from Haas et al (2009).⁴

CI: confidence interval; RDS: respiratory distress syndrome.

^a Maternal adverse events are those that required discontinuation of the medication.

All tocolytic agents were significantly better than placebo/control at delaying delivery for 48 hours and for 7 days; none significantly improved delivery rates until after 37 weeks of gestation. The rate of discontinuation due to adverse events was significantly higher for betamimetics than placebo/control but not for any other categories of medication.

Reviewers also conducted a decision analysis to determine the optimal medication based on the balance of benefits and risks. The decision analysis model found that prostaglandin inhibitors might be the superior agent up to 32 weeks of gestation due to a high effectiveness at delaying delivery by at least 7 days and offering a low rate of adverse events. Calcium channel blockers were the superior agent for delaying delivery until 37 weeks. Compared with other tocolytics, calcium channel blockers reduced the incidence of birth within 7 days of treatment (relative risk [RR], 0.76; 95% confidence interval [CI], 0.60 to 0.97) and before 34 weeks of gestation (RR=0.83; 95% CI, 0.69 to 0.99).

In another review, Haas et al (2012) conducted a systematic review and network meta-analysis in which direct and indirect evidence on relative impacts of tocolytics on health outcomes were pooled simultaneously.5 Consequently, the analysis was not limited to comparisons in head-to-head trials that the research team had addressed in 2009. Reviewers identified 95 RCTs: 25 contained a placebo arm, 60 included betamimetics, 29 included magnesium sulfate, 29 included calcium channel blockers, 18 included prostaglandin inhibitors, 13 included oxytocin receptor blockers, 4 included nitrates, and 5 included “other” drugs. Reviewers assumed that all drugs in the same class had a similar effect.

Fifty-five studies were included in the network analysis for the primary efficacy outcome, delivery delayed by 48 hours. All active classes were found to be superior to placebo. The analysis also suggested that prostaglandin inhibitors had a greater beneficial effect than any other active class of medication, and calcium channel blockers and magnesium sulfate had a greater beneficial effect than oxytocin receptor blockers, nitrates, and betamimetics. Prostaglandin inhibitors had an 83% probability of being the “best” class of active medications. The probability of being ranked among the 3 most efficacious classes was 96% for prostaglandin inhibitors, 63% for magnesium sulfate, 57% for calcium channel blockers, 33% for betamimetics, 24% for nitrates, and 14% for oxytocin receptor blockers.

Forty trials were included in the network analysis for the outcome of neonatal mortality. There was no clear evidence for any class of medication being superior to placebo. Calcium channel blockers were found to be the “best” class, but the probability was only 41%, which reflects the considerable uncertainty in the estimate. Prostaglandin inhibitors had a 28% chance of being the “best” class, which was the second highest probability of any class. Similarly, calcium channel blockers were the “best” class for reducing neonatal respiratory distress syndrome (RDS), but the probability was only 47%.

Fifty-eight trials were included in the network analysis for the outcome all-cause maternal side effects. Other than placebo, prostaglandin inhibitors had a 79% chance of being the drug class with the fewest maternal side effects. This was followed by oxytocin receptor blockers, at 70% probability, and calcium channel blockers, at 15%.

Overall, prostaglandin inhibitors and calcium channel blockers had the highest probability of being the best classes of medication based on all 4 outcome measures: delivery delayed by 48 hours, neonatal mortality, neonatal RDS, and maternal side effects.

Several systematic reviews and meta-analyses have focused on a single tocolytic class or agent. A Cochrane review by Flenady et al (2014) identified 38 trials evaluating calcium channel blockers for tocolysis (total N=3550 women). 6 The calcium channel blocker was nifedipine in 35 trials and nicardipine in the other 3. Thirty-five trials used other tocolytic agents as the comparator (19 used betamimetics), one compared doses of nifedipine, and the other two compared calcium channel blockers with placebo or no intervention. Only 1 trial was double-blinded. Reviewers evaluated several primary and secondary outcomes and conducted pooled analyses when sufficient data were available. Findings were mixed among primary outcomes, but several favored calcium channel blockers over betamimetics. There was a significantly lower rate of “very preterm birth” before 34 weeks of gestation with calcium channel blockers compared with betamimetics (6 trials; RR=0.78; 95% CI, 0.66 to 0.93) and a significantly lower rate of maternal adverse events (15 trials; RR=0.36; 95% CI, 0.24 to 0.53). The incidence of birth less than 48 hours after trial entry and the rate of perinatal mortality did not differ significantly between calcium channel blockers and other tocolytic agents. Among secondary outcome measures, there was a significantly lower rate of preterm birth before completion of 37 weeks of gestation with calcium channel blockers compared with betamimetics (13 trials; RR=0.89; 95% CI, 0.80 to 0.98), and there were too few studies to compare with other tocolytic agents. Reviewers noted that the quality of studies (eg, lack of blinding, limited placebo controls) limited the ability to draw firm conclusions about the efficacy of calcium channel blockers compared with other tocolytic agents.

An updated Cochrane review by Flenady et al (2014) identified 14 trials on oxytocin inhibitors (total N=2485 women). ⁷ The control intervention was a placebo in 4 trials, betamimetics in 8 trials, and a calcium channel blocker in 2 studies. Pooled analyses did not demonstrate the superiority of oxytocin receptor antagonists over betamimetics or placebo in terms of reduction in preterm birth or adverse neonatal outcomes (note that oxytocin inhibitors are not approved by the Food and Drug Administration for use in the United States).

In another Cochrane review, Crowther et al (2014) identified 37 trials (total N=3571 women) evaluating the use of tocolysis. 8 Comparison interventions included other tocolytic drugs, predominantly betamimetics, nitroglycerine, human chorionic gonadotropin, saline, and dextrose. No placebo-controlled trials were identified. Pooled analyses found no statistically significant differences between magnesium sulfate and comparator interventions for outcomes including birth less than 48 hours after trial entry, serious infant adverse events, and preterm birth before 37 weeks of gestation.

Conde-Agudelo et al (2011) reviewed trials on nifedipine.9 They identified 26 randomized trials (total N=2179 women) comparing nifedipine with placebo, no treatment, or a different tocolytic agent. Twentythree trials evaluated acute tocolysis and 3 evaluated maintenance tocolysis (discussed later in the Rationale section). Findings were mixed. Pooled analyses of trials comparing nifedipine with betaagonists found significantly lower rates of delivery within 7 days of treatment (10 trials; RR=0.82; 95% CI, 0.70 to 0.97) and preterm birth before 34 weeks of gestation (5 trials; RR=0.77; 95% CI, 0.66 to 0.91), but no significant differences in the rates of preterm delivery within 48 hours of treatment (13 trials; RR=0.84, 95% CI, 0.68 to 1.05) or preterm delivery before 37 weeks of gestation (9 trials; RR=0.97; 95% CI, 0.87 to 1.08). There were no significant differences in any of the preterm delivery variables when nifedipine was compared with magnesium sulfate, but the number of trials and total sample sizes were both small, making it difficult to draw conclusions about comparative efficacy.

A Cochrane review by King et al (2005) included 13 trials on cyclooxygenase inhibitors (total N=713 women); indomethacin was used in 10 of the trials.10 Only 1 trial compared cyclooxygenase inhibitors with placebo. Pooled analysis of studies comparing cyclooxygenase inhibitors with other tocolytics found a significant reduction in the incidence of birth before 37 weeks of gestation (RR=0.53; 54 women). Reviewers noted that sample sizes were small, and thus estimates were imprecise and not definitive.

In addition to these reviews of single agents, Vogel et al (2014) published a Cochrane review on combinations of tocolytic agents for preventing preterm labor.11 Reviewers searched for RCTs comparing any combination of tocolytic agents with any other treatment (including other combinations, single tocolytic agents, no intervention, or placebo). Eleven trials evaluating 7 different comparisons met reviewers’ inclusion criteria; two of them did not report relevant outcome data. Thus, few studies with small combined sample sizes were available for analysis, and reviewers could not pool data or draw conclusions about the safety and efficacy of any combination of tocolytics vs any comparator intervention.

Section Summary: Acute Tocolysis Multiple

RCTs and systematic reviews have found tocolytics to be effective at decreasing rates of preterm birth in women with preterm labor (eg, delaying delivery for 7 days and/or decreasing rates of delivery before 34 or 37 weeks of gestation). The optimal first-line medication is uncertain. A 2012 network metaanalysis suggested that prostaglandin inhibitors and calcium channel blockers may have greater efficacy and fewer adverse events than other classes of medication. However, there was considerable uncertainty in the estimates of which class of medication was “best” for each outcome. Cochrane reviews of various tocolytic agents have not found any single agent to be superior to another.

For individuals who have preterm labor or threatened preterm labor who receive acute tocolytic therapy, the evidence includes multiple randomized controlled trials and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Overall, the body of evidence has shown that the commonly used tocolytic agents presented herein are effective at inducing tocolysis in patients with preterm labor or threatened preterm labor. Data have suggested that oral terbutaline is associated with more adverse events than parenteral terbutaline for acute tocolysis. Each medication has a different risk-benefit profile, and there is no clear first-line tocolytic agent. The evidence is sufficient to determine that the technology results in a meaningful improvement in the net health outcome.

Population Reference No. 2 Policy Statement

MAINTENANCE OF TOCOLYSIS

Clinical Context and Therapy Purpose

The purpose of maintenance of tocolysis in patients who have had preterm labor is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The question addressed in this evidence review is: Does maintenance with tocolytic agents improve the net health outcome in women who have had successful tocolytic therapy for preterm labor?

The following PICOTS were used to select literature to inform this review.

Patients

The relevant population of interest is women treated successfully with tocolytic agents for preterm labor.

Interventions

The therapy being considered is maintenance tocolysis. Tocolytic medications include terbutaline sulfate, calcium channel blockers (eg, nifedipine), magnesium sulfate, oxytocin receptor antagonists (eg, atosiban), prostaglandin inhibitors (eg, indomethacin), and nitrates (eg, nitroglycerin).

Comparators

The following practice is currently being used to make decisions about use of maintenance tocolysis to prevent recurrence of preterm labor: no tocolytic therapy.

Outcomes

The outcomes of interest are the gestational age at birth, morbidity and mortality of the infant, and adverse effects of treatment on the mother.

Timing

The timing is up to 37 weeks gestation.

Setting

Therapy is administered in an inpatient care setting by a specialist (eg, obstetrician-gynecologist).

Systematic Reviews

A Cochrane review by Papatsonis et al (2013), evaluating maintenance therapy with oxytocin antagonists, identified only ¹ trial.¹² This trial, by Valenzuela et al (2000), did not find that atosiban reduced the rate of preterm birth after threatened preterm birth compared with placebo.¹³

Another Cochrane review, conducted by Naik Gaunekar et al (2013), identified 6 RCTs on maintenance therapy with calcium channel blockers.14 Nifedipine was used in all trials, and a total of 794 women were included. The comparison intervention was placebo in 3 trials and no treatment in the other 3 trials. Pooled analyses did not find that calcium channel blockers significantly reduced the rate of preterm birth before 37 weeks (5 trials; RR=0.97; 95% CI, 0.87 to 1.09) or 34 weeks (3 trials; RR=1.07; 95% CI, 0.88 to 1.30). A pooled analysis of 2 trials did not find significant differences between calcium channel blockers and controls for the outcome birth within 48 hours of treatment. There were insufficient data to draw conclusions about other outcomes.

Dodd et al (2012) conducted a Cochrane review on oral betamimetics for maintenance tocolysis after threatened preterm labor.15 They identified 13 RCTs, some of which had more than 2 arms. There were 10 comparisons of a betamimetic and placebo or no treatment, 1 comparison of a betamimetic and indomethacin, 1 comparison between 2 different betamimetics, and 3 comparisons between a betamimetic and magnesium. Data could not be pooled in a number of outcomes due to insufficient data on a particular comparison. In a pooled analysis of 6 studies, there was no statistically significant difference in the rate of preterm birth before 37 weeks in patients receiving a maintenance betamimetic vs placebo or no treatment (RR=1.11; 95% CI, 0.91 to 1.35). In other pooled analyses of findings from studies comparing maintenance betamimetics with placebo or no treatment, there were no statistically significant differences between groups in birth weight (7 studies; mean difference, 4.13; 95% CI, -91.89 to 100.16), risk of perinatal mortality (6 studies; RR=2.41; 95% CI, 0.86 to 6.74), or risk of RDS in infants (6 studies; RR=1.10; 95% CI, 0.61 to 1.98).

A review by Han et al (2010) evaluated magnesium maintenance therapy and did not find a statistically significant effect of that maintenance therapy on prevention of preterm birth before 37 weeks of gestation.16 A meta-analysis of 2 studies (n=99 patients) that compared magnesium therapy with placebo or no treatment found a combined RR of 1.05 (99% CI, 0.80 to 1.40). Two studies (n=100 patients) were also available for a meta-analysis of studies comparing magnesium therapy with an alternative treatment. In that analysis, the combined RR was 0.99 (95% CI, 0.57 to 1.72).

The Conde-Agudelo systematic review and meta-analysis (2011), described earlier, included 3 studies evaluating a calcium channel blocker (nifedipine) for maintenance tocolysis.9 A pooled analysis of these 3 trials (n=215 patients) did not find a significant difference in the rate of preterm birth before 37 weeks of gestation with nifedipine or with placebo or no treatment (RR=0.87; 97% CI, 0.69 to 1.08). There were insufficient data to conduct pooled analyses on other pregnancy outcome variables.

A health technology assessment by Honest et al (2009) addressed a wider range of maintenance tocolytic agents.17 However, for the outcomes prevention of preterm birth before 34 or 37 weeks of gestation, there were only a sufficient number of trials to conduct pooled analyses for 2 comparisons. Neither analysis found a statistically significant benefit of tocolysis. In a pooled analysis comparing magnesium maintenance therapy with other tocolytic agents, the combined RR was 0.98 (95% CI, 0.56 to 1.72). In addition, a pooled analysis of 4 trials (n=384 patients) did not find a significant benefit of oral betamimetics compared with placebo or no treatment for preventing preterm birth before 37 weeks of gestation. The combined RR was 1.08 (95% CI, 0.88 to 1.22).

Nonrandomized Studies

Follow-up data from the APOSTEL II trial were reported by van Vliet et al (2016) on maintenance tocolysis using nifedipine.¹⁸ Two-year outcomes data from this RCT were available for 135 (52.5%) of 276 participants. Outcomes were mixed for infants of women in the nifedipine maintenance group compared with the placebo group. Those on nifedipine maintenance doses had a higher incidence of fine motor problems (22% vs 8%, odds ratio, 3.43; 95% CI, 1.29 to 9.14) and a lower incidence of poor problemsolving ability (22% vs 29%; odds ratio, 0.27; 95% CI, 0.08 to 0.95).

Section Summary: Maintenance of Tocolysis

There are fewer RCTs comparing maintenance tocolysis with acute tocolysis. RCTs and systematic reviews on maintenance tocolysis have not found that tocolytic agents significantly improve health outcomes. Moreover, there are insufficient data from placebo-controlled trials.

For individuals who have successful acute tocolysis for preterm labor who receive maintenance tocolytic therapy, the evidence includes randomized controlled trials and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Studies have generally not found that maintenance tocolysis lowers the rate of preterm birth or perinatal mortality, or increases the birth weight. The evidence is insufficient to determine the effects of the technology on health outcomes.

SUMMARY OF EVIDENCE

For individuals who have preterm labor or threatened preterm labor who receive acute tocolytic therapy, the evidence includes multiple RCTs and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Overall, the body of evidence has shown that the commonly used tocolytic agents presented herein are effective at inducing tocolysis in patients with preterm labor or threatened preterm labor. Data have suggested that oral terbutaline is associated with more adverse events than parenteral terbutaline for acute tocolysis. Each medication has a different risk-benefit profile, and there is no clear first-line tocolytic agent. The evidence is sufficient to determine that the technology results in a meaningful improvement in the net health outcome. For individuals who have successful acute tocolysis for preterm labor who receive maintenance tocolytic therapy, the evidence includes randomized controlled trials and systematic reviews. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related morbidity. Studies have generally not found that maintenance tocolysis lowers the rate of preterm birth or perinatal mortality, or increases the birth weight. The evidence is insufficient to determine the effects of the technology on health outcomes.

Supplemental Information

CLINICAL INPUT FROM PHYSICIAN SPECIALTY SOCIETIES AND ACADEMIC MEDICAL CENTERS

While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted. In response to requests, input was received from 2 physician specialty societies and 4 academic medical centers while this policy was under review in 2012. There was a consensus that acute tocolysis may be considered medically necessary to induce tocolysis in patients with preterm labor and near consensus that preterm should be defined as “<37 weeks” gestational age. There was mixed input on the investigational policy statement on maintenance tocolysis (beyond 48-72 hours).

Practice Guidelines and Position Statements

American College of Obstetricians and Gynecologists

The American College of Obstetricians and Gynecologists (2016) updated its practice bulletin on the management of preterm labor. 19 The 2016 bulletin contained the following relevant recommendations based on “good and consistent” scientific evidence:

 “A single course of corticosteroids is recommended for pregnant women between 24 weeks of gestation and 34 weeks of gestation who are at risk of preterm delivery within 7 days.

 Accumulated available evidence suggests that magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks of gestation. Hospitals that elect to use magnesium sulfate for fetal neuroprotection should develop uniform and specific guidelines for their departments regarding inclusion criteria, treatment regimens, concurrent tocolysis, and monitoring in accordance with one of the larger trials.

 The evidence supports the use of first-line tocolytic treatment with beta-adrenergic agonist therapy, calcium channel blockers, or NSAIDs [non-steroidal anti-inflammatory drugs] for shortterm prolongation of pregnancy (up to 48 hours) to allow for the administration of antenatal steroids.

 Maintenance therapy with tocolytics is ineffective for preventing preterm birth and improving neonatal outcomes and is not recommended for this purpose.

 Antibiotics should not be used to prolong gestation or improve neonatal outcomes in women with pre-term labor and intact membranes.”

National Institute for Health and Care Excellence

A 2015 guidance from the National Institute for Health and Care Excellence on preterm labor and birth made the following recommendations on tocolysis²⁰:

1.8.2 “Consider nifedipine for tocolysis for women between 24+0 and 25+6 weeks of pregnancy who have intact membranes and are in suspected preterm labour.

1.8.3 Offer nifedipine for tocolysis to women between 26+0 and 33+6 weeks of pregnancy who have intact membranes and are in suspected or diagnosed preterm labour.

1.8.4 If nifedipine is contraindicated, offer oxytocin receptor antagonists for tocolysis.

1.8.5 Do not offer betamimetics for tocolysis.”

1.9.1 “For women between 23+0 and 23+6 weeks of pregnancy who are in suspected or established preterm labour, are having a planned preterm birth or have P-PROM [preterm prelabour rupture of membranes] … discuss with the woman (and her family members or carers as appropriate) the use of maternal corticosteroids in the context of her individual circumstances.

1.9.2 Consider maternal corticosteroids for women between 24+0 and 25+6 weeks of pregnancy who are in suspected or established preterm labour, are having a planned preterm birth or have PPROM.

1.9.3 Offer maternal corticosteroids to women between 26+0 and 33+6 weeks of pregnancy who are in suspected, diagnosed or established preterm labour, are having a planned preterm birth or have P-PROM.

1.9.4 Consider maternal corticosteroids for women between 34+0 and 35+6 weeks of pregnancy who are in suspected, diagnosed or established preterm labour, are having a planned preterm birth or have P-PROM.”

1.10.1 “Offer intravenous magnesium sulfate for neuroprotection of the baby to women between 24+0 and 29+6 weeks of pregnancy who are:

 in established preterm labour or

 having a planned preterm birth within 24 hours.

1.10.2 Consider intravenous magnesium sulfate for neuroprotection of the baby for women between 30+0 and 33+6 weeks of pregnancy who are:

 in established preterm labour or

 having a planned preterm birth within 24 hours.”

Medicare National Coverage

There is no national coverage determination. In the absence of a national coverage determination, coverage decisions are left to the discretion of local Medicare carriers.

ONGOING AND UNPUBLISHED CLINICAL TRIALS

A search of ClinicalTrials.gov in July 2018 did not identify any ongoing or unpublished trials that would likely influence this review.

References

1. American College of Obstetricians Gynecologists, Committee on Practice Bulletins-Obstetrics. ACOG practice bulletin no. 127: Management of preterm labor. Obstet Gynecol. Jun 2012;119(6):1308-1317. PMID 22617615

2. Food and Drug Administration (FDA). FDA Drug Safety Communication: New warnings against use of terbutaline to treat preterm labor. February 17, 2011; www.fda.gov/drugs/drugsafety/ucm243539.htm. Accessed July 22, 2018.

3. Rodier P, Miller RK, Brent RL. Does treatment of premature labor with terbutaline increase the risk of autism spectrum disorders? [editorial]. Am J Obstet Gynecol. Feb 2011;204(2):91-94. PMID 21284962

4. Haas DM, Imperiale TF, Kirkpatrick PR, et al. Tocolytic therapy: a meta-analysis and decision analysis. Obstet Gynecol. Mar 2009;113(3):585-594. PMID 19300321

5. Haas DM, Caldwell DM, Kirkpatrick P, et al. Tocolytic therapy for preterm delivery: systematic review and network meta-analysis. BMJ. Oct 2012;345:e6226. PMID 23048010

6. Flenady V, Wojcieszek AM, Papatsonis DN, et al. Calcium channel blockers for inhibiting preterm labour and birth. Cochrane Database Syst Rev. Jun 05 2014;6(6):CD002255. PMID 24901312

7. Flenady V, Reinebrant HE, Liley HG, et al. Oxytocin receptor antagonists for inhibiting preterm labour. Cochrane Database Syst Rev. Jun 06 2014;6(6):CD004452. PMID 24903678

8. Crowther CA, Brown J, McKinlay CJ, et al. Magnesium sulphate for preventing preterm birth in threatened preterm labour. Cochrane Database Syst Rev. Aug 15 2014;8(8):CD001060. PMID 25126773

9. Conde-Agudelo A, Romero R, Kusanovic JP. Nifedipine in the management of preterm labor: a systematic review and metaanalysis. Am J Obstet Gynecol. Feb 2011;204(2):134.e131-120. PMID 21284967

10. King J, Flenady V, Cole S, et al. Cyclo-oxygenase (COX) inhibitors for treating preterm labour. Cochrane Database Syst Rev. Apr 18 2005(2):CD001992. PMID 15846626

11. Vogel JP, Nardin JM, Dowswell T, et al. Combination of tocolytic agents for inhibiting preterm labour. Cochrane Database Syst Rev. Jul 11 2014;7(7):CD006169. PMID 25010869

12. Papatsonis DN, Flenady V, Liley HG. Maintenance therapy with oxytocin antagonists for inhibiting preterm birth after threatened preterm labour. Cochrane Database Syst Rev. Oct 13 2013;10(10):CD005938. PMID 24122673

13. Valenzuela GJ, Sanchez-Ramos L, Romero R, et al. Maintenance treatment of preterm labor with the oxytocin antagonist atosiban. The Atosiban PTL-098 Study Group. Am J Obstet Gynecol. May 2000;182(5):1184-1190. PMID 10819856

14. Naik Gaunekar N, Raman P, Bain E, et al. Maintenance therapy with calcium channel blockers for preventing preterm birth after threatened preterm labour. Cochrane Database Syst Rev. Oct 31 2013;10(10):CD004071. PMID 24173691

15. Dodd JM, Crowther CA, Middleton P. Oral betamimetics for maintenance therapy after threatened preterm labour. Cochrane Database Syst Rev. Dec 12 2012;12:CD003927. PMID 23235600

16. Han S, Crowther CA, Moore V. Magnesium maintenance therapy for preventing preterm birth after threatened preterm labour. Cochrane Database Syst Rev. Jul 07 2010(7):CD000940. PMID 20614423

17. Honest H, Forbes CA, Duree KH, et al. Screening to prevent spontaneous preterm birth: systematic reviews of accuracy and effectiveness literature with economic modelling. Health Technol Assess. Sep 2009;13(43):1-627. PMID 19796569

18. van Vliet E, Seinen L, Roos C, et al. Maintenance tocolysis with nifedipine in threatened preterm labour: 2-year follow up of the offspring in the APOSTEL II trial. BJOG. Jun 2016;123(7):1107-1114. PMID 26330379

19. American College of Obstetricians and Gynecologists, Committee on Practice Bulletins-Obstetrics. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol. Oct 2016;128(4):e155-164. PMID 27661654

20. National Institute for Health and Care Excellence (NICE). Preterm labour and birth [NG25]. 2015; https://www.nice.org.uk/guidance/ng25. Accessed July 22, 2018.

Codes

Applicable Modifiers

N/A

Policy History