Effects of prolonged versus acute indomethacin therapy in very low birth-weight infants with patent ductus arteriosus

Interventions for patent ductus arteriosus (PDA) in preterm infants: an overview of Cochrane Systematic Reviews

BACKGROUND

Patent ductus arteriosus (PDA) is associated with significant morbidity and mortality in preterm infants. Several non-pharmacological, pharmacological, and surgical approaches have been explored to prevent or treat a PDA.

OBJECTIVES

To summarise Cochrane Neonatal evidence on interventions (pharmacological or surgical) for the prevention of PDA and related complications, and interventions for the management of asymptomatic and symptomatic PDA in preterm infants.

METHODS

We searched the Cochrane Database of Systematic Reviews on 20 October 2022 for ongoing and published Cochrane Reviews on the prevention and treatment of PDA in preterm (< 37 weeks' gestation) or low birthweight (< 2500 g) infants. We included all published Cochrane Reviews assessing the following categories of interventions: pharmacological therapy using prostaglandin inhibitor drugs (indomethacin, ibuprofen, and acetaminophen), adjunctive pharmacological interventions, invasive PDA closure procedures, and non-pharmacological interventions. Two overview authors independently checked the eligibility of the reviews retrieved by the search, and extracted data from the included reviews using a predefined data extraction form. Any disagreements were resolved by discussion with a third overview author. Two overview authors independently assessed the methodological quality of the included reviews using the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews) tool. We reported the GRADE certainty of evidence as assessed by the respective review authors using summary of findings tables.

MAIN RESULTS

We included 16 Cochrane Reviews, corresponding to 138 randomised clinical trials (RCT) and 11,856 preterm infants, on the prevention and treatment of PDA in preterm infants. One of the 16 reviews had no included studies, and therefore, did not contribute to the results. Six reviews reported on prophylactic interventions for the prevention of PDA and included pharmacological prophylaxis with prostaglandin inhibitor drugs, prophylactic surgical PDA ligation, and non-pharmacologic interventions (chest shielding during phototherapy and restriction of fluid intake); one review reported on the use of indomethacin for the management of asymptomatic PDA; nine reviews reported on interventions for the management of symptomatic PDA, and included pharmacotherapy with prostaglandin inhibitor drugs in various routes and dosages, surgical PDA ligation, and adjunct therapies (use of furosemide and dopamine in conjunction with indomethacin). The quality of reviews varied. Two reviews were assessed to be high quality, seven reviews were of moderate quality, five of low quality, while two reviews were deemed to be of critically low quality. For prevention of PDA, prophylactic indomethacin reduces severe intraventricular haemorrhage (IVH; relative risk (RR) 0.66, 95% confidence interval (CI) 0.53 to 0.82; 14 RCTs, 2588 infants), and the need for invasive PDA closure (RR 0.51, 95% CI 0.37 to 0.71; 8 RCTs, 1791 infants), but it does not appear to affect the composite outcome of death or moderate/severe neurodevelopmental disability (RR 1.02, 95% CI 0.90 to 1.15; 3 RCTs, 1491 infants). Prophylactic ibuprofen probably marginally reduces severe IVH (RR 0.67, 95% CI 0.45 to 1.00; 7 RCTs, 925 infants; moderate-certainty evidence), and the need for invasive PDA closure (RR 0.46, 95% CI 0.22 to 0.96; 7 RCTs, 925 infants; moderate-certainty evidence). The evidence is very uncertain on the effect of prophylactic acetaminophen on severe IVH (RR 1.09, 95% CI 0.07 to 16.39; 1 RCT, 48 infants). Necrotising enterocolitis (NEC) was lower with both prophylactic surgical ligation (RR 0.25, 95% CI 0.08 to 0.83; 1 RCT, 84 infants), and fluid restriction (RR 0.43, 95% CI 0.21 to 0.87; 4 RCTs, 526 infants). For treatment of asymptomatic PDA, indomethacin appears to reduce the development of symptomatic PDA post-treatment (RR 0.36, 95% CI 0.19 to 0.68; 3 RCTs, 97 infants; quality of source review: critically low). For treatment of symptomatic PDA, all available prostaglandin inhibitor drugs appear to be more effective in closing a PDA than placebo or no treatment (indomethacin: RR 0.30, 95% CI 0.23 to 0.38; 10 RCTs, 654 infants; high-certainty evidence; ibuprofen: RR 0.62, 95% CI 0.44 to 0.86; 2 RCTs, 206 infants; moderate-certainty evidence; early administration of acetaminophen: RR 0.35, 95% CI 0.23 to 0.53; 2 RCTs, 127 infants; low-certainty evidence). Oral ibuprofen appears to be more effective in PDA closure than intravenous (IV) ibuprofen (RR 0.38, 95% CI 0.26 to 0.56; 5 RCTs, 406 infants; moderate-certainty evidence). High-dose ibuprofen appears to be more effective in PDA closure than standard-dose ibuprofen (RR 0.37, 95% CI 0.22 to 0.61; 3 RCTs, 190 infants; moderate-certainty evidence). With respect to adverse outcomes, compared to indomethacin administration, NEC appears to be lower with ibuprofen (any route; RR 0.68, 95% CI 0.49 to 0.94; 18 RCTs, 1292 infants; moderate-certainty evidence), oral ibuprofen (RR 0.41, 95% CI 0.23 to 0.73; 7 RCTs, 249 infants; low-certainty evidence), and with acetaminophen (RR 0.42, 95% CI 0.19 to 0.96; 4 RCTs, 384 infants; low-certainty evidence). However, NEC appears to be increased with a prolonged course of indomethacin versus a shorter course (RR 1.87, 95% CI 1.07 to 3.27; 4 RCTs, 310 infants).

AUTHORS' CONCLUSIONS

This overview summarised the evidence from 16 Cochrane Reviews of RCTs regarding the effects of interventions for the prevention and treatment of PDA in preterm infants. Prophylactic indomethacin reduces severe IVH, but does not appear to affect the composite outcome of death or moderate/severe neurodevelopmental disability. Prophylactic ibuprofen probably marginally reduces severe IVH (moderate-certainty evidence), while the evidence is very uncertain on the effect of prophylactic acetaminophen on severe IVH. All available prostaglandin inhibitor drugs appear to be effective in symptomatic PDA closure compared to no treatment (high-certainty evidence for indomethacin; moderate-certainty evidence for ibuprofen; low-certainty evidence for early administration of acetaminophen). Oral ibuprofen appears to be more effective in PDA closure than IV ibuprofen (moderate-certainty evidence). High dose ibuprofen appears to be more effective in PDA closure than standard-dose ibuprofen (moderate-certainty evidence). There are currently two ongoing reviews, one on fluid restriction for symptomatic PDA, and the other on invasive management of PDA in preterm infants.

Efficacy and safety of pharmacological treatments for patent ductus arteriosus closure: A systematic review and network meta-analysis of clinical trials and observational studies

Efficacy and safety profiles of different pharmacological interventions used to treat patent ductus arteriosus (PDA) are relatively unexplored. Integrating the findings of randomized clinical trials (RCTs) with those from observational studies may provide key evidence on this important issue. We aimed at estimating the relative likelihood of failure to close the PDA, need for surgical closure, and occurrence of adverse events among preterm and full-term infants treated with indomethacin, ibuprofen, or acetaminophen, placebo, or no treatment including both RCTs and observational studies. We searched PubMed, Embase, and the Register of Controlled Trials from inception to October 30, 2018. We first estimated proportions of subjects with failure to close the PDA, subjects in whom surgical closure was performed after pharmacological treatment, death, and subjects with selected adverse events (AEs). These estimates were obtained using frequentist random-effect meta-analysis of arm-specific proportions. We then compared active drugs with each other and with control (either placebo or no treatment) by summarizing results at the end of treatment reported in the papers, regardless of number of administration(s), dose, route and type of administration, and study design and quality. We also summarized primary outcome results separately at first, second and third cycles of treatment. These estimates were obtained using Bayesian random-effects network meta-analysis for mixed comparisons, and frequentist random-effect pairwise meta-analysis for direct comparisons. We included 64 RCTs and 24 observational studies including 14,568 subjects (5339 in RCTs and 9229 in observational studies, 8292 subjects received indomethacin, 4761 ibuprofen, 574 acetaminophen, and 941 control (including placebo or no intervention).The proportion of subjects with failure to close the PDA was 0.24 (95% Confidence Interval, CI: 0.20, 0.29) for indomethacin, 0.18 (0.14, 0.22) for ibuprofen, 0.19 (0.09, 0.30) for acetaminophen, and 0.59 (0.48, 0.69) for control. At end of treatment, compared to control, we found inverse associations between all active drugs and failure to close PDA (for indomethacin Odds Ratio, OR, was 0.17 [95% Credible Interval, CrI: 0.11-0.24], ibuprofen 0.19 [0.12-0.28], and acetaminophen 0.15 [0.09-0.26]), without differences among active drugs. We showed inverse associations between effective drugs and need for surgical closure, as compared to control (for indomethacin OR was 0.28 [0.15-0.50], ibuprofen 0.30 [0.16-0.54], and acetaminophen 0.19 [0.07-0.46]), without differences among drugs. Indomethacin was directly associated with intraventricular hemorrhage (IVH) (1.27; 1.00, 1.62) compared to ibuprofen, and to oliguria as compared to ibuprofen (3.92; 1.69, 9.82) or acetaminophen (10.8; 1.86, 93.1). In conclusion, active pharmacological treatment, with indomethacin, ibuprofen, or acetaminophen, is inversely associated with failure to close the PDA compared to non-treatment. Ibuprofen should be preferred to indomethacin to avoid occurrence of IVH or oliguria, acetaminophen should be preferred to indomethacin to avoid oliguria.

Association of Placebo, Indomethacin, Ibuprofen, and Acetaminophen With Closure of Hemodynamically Significant Patent Ductus Arteriosus in Preterm Infants: A Systematic Review and Meta-analysis

IMPORTANCE

Despite increasing emphasis on conservative management of patent ductus arteriosus (PDA) in preterm infants, different pharmacotherapeutic interventions are used to treat those developing a hemodynamically significant PDA.

OBJECTIVES

To estimate the relative likelihood of hemodynamically significant PDA closure with common pharmacotherapeutic interventions and to compare adverse event rates.

DATA SOURCES AND STUDY SELECTION

The databases of MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception until August 15, 2015, and updated on December 31, 2017, along with conference proceedings up to December 2017. Randomized clinical trials that enrolled preterm infants with a gestational age younger than 37 weeks treated with intravenous or oral indomethacin, ibuprofen, or acetaminophen vs each other, placebo, or no treatment for a clinically or echocardiographically diagnosed hemodynamically significant PDA.

DATA EXTRACTION AND SYNTHESIS

Data were independently extracted in pairs by 6 reviewers and synthesized with Bayesian random-effects network meta-analyses.

MAIN OUTCOMES AND MEASURES

Primary outcome: hemodynamically significant PDA closure; secondary: included surgical closure, mortality, necrotizing enterocolitis, and intraventricular hemorrhage.

RESULTS

In 68 randomized clinical trials of 4802 infants, 14 different variations of indomethacin, ibuprofen, or acetaminophen were used as treatment modalities. The overall PDA closure rate was 67.4% (2867 of 4256 infants). A high dose of oral ibuprofen was associated with a significantly higher odds of PDA closure vs a standard dose of intravenous ibuprofen (odds ratio [OR], 3.59; 95% credible interval [CrI], 1.64-8.17; absolute risk difference, 199 [95% CrI, 95-258] more per 1000 infants) and a standard dose of intravenous indomethacin (OR, 2.35 [95% CrI, 1.08-5.31]; absolute risk difference, 124 [95% CrI, 14-188] more per 1000 infants). Based on the ranking statistics, a high dose of oral ibuprofen ranked as the best pharmacotherapeutic option for PDA closure (mean surface under the cumulative ranking [SUCRA] curve, 0.89 [SD, 0.12]) and to prevent surgical PDA ligation (mean SUCRA, 0.98 [SD, 0.08]). There was no significant difference in the odds of mortality, necrotizing enterocolitis, or intraventricular hemorrhage with use of placebo or no treatment compared with any of the other treatment modalities.

CONCLUSIONS AND RELEVANCE

A high dose of oral ibuprofen was associated with a higher likelihood of hemodynamically significant PDA closure vs standard doses of intravenous ibuprofen or intravenous indomethacin; placebo or no treatment did not significantly change the likelihood of mortality, necrotizing enterocolitis, or intraventricular hemorrhage.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42015015797.

Pharmacological Closure of Patent Ductus Arteriosus: Selecting the Agent and Route of Administration

Opinions are divided regarding the management of a persistently patent ductus arteriosus (PDA). Some of the adverse effects associated with a large hemodynamically significant duct, including prolonged ventilation, pulmonary hemorrhage, bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and mortality, indicate that active management of infants with large ductal shunts may sometimes be necessary. Indomethacin and ibuprofen are the two US FDA-approved cyclooxygenase (COX) inhibitors used for the closure of a ductus in preterm babies. Both these drugs are effective in 70-80% of extremely low birthweight infants. Treatment with COX inhibitors may be associated with renal impairment, gastrointestinal hemorrhage, NEC, and spontaneous intestinal perforation when given concurrently with steroids, as well as changes in cerebrovascular auto-regulation. Ibuprofen appears to be a better choice for PDA closure, with a better side effect profile and efficacy that equals that of indomethacin. However, long-term outcome studies of ibuprofen are lacking, and prophylactic ibuprofen is ineffective in decreasing severe IVH. The choice of one drug over the other also depends on local availability of both drugs and the intravenous or enteral preparation. The oral preparation of ibuprofen appears as effective as the intravenous preparation. The use of paracetamol to close a hemodynamically significant PDA has increased in recent years. Paracetamol also decreases prostacyclin synthesis; however, unlike COX inhibitors, it does not have a peripheral vaso-constrictive effect and can be given to infants with contraindications to non-steroidal anti-inflammatory drugs. It appears to have similar efficacy based on limited data available from randomized trials. Until more data are available on efficacy, safety, and long-term outcomes, it cannot be recommended as the first choice.

Prophylactic intravenous indomethacin for preventing mortality and morbidity in preterm infants

BACKGROUND

Persistent patent ductus arteriosus (PDA) is associated with mortality and morbidity in preterm infants. Prostaglandin synthetase inhibitors such as indomethacin promote PDA closure but also have potential side effects. The effect of the prophylactic use of indomethacin, where infants who may not have gone on to develop a symptomatic PDA would be exposed to indomethacin, warrants particular scrutiny.

OBJECTIVES

To determine the effect of prophylactic indomethacin on mortality and morbidity in preterm infants.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 5, 2010), MEDLINE, EMBASE and CINAHL (until April 2010), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared prophylactic indomethacin versus placebo or no drug in preterm infants.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group were used, with separate evaluation of trial quality and data extraction by two review authors.

MAIN RESULTS

Nineteen eligible trials in which 2872 infants participated were identified. Most participants were very low birth weight, but the largest single trial restricted participation to extremely low birth weight infants (N = 1202). The trials were generally of good quality.The incidence of symptomatic PDA [typical relative risk (RR) 0.44, 95% confidence interval (CI) 0.38 to 0.50] and PDA surgical ligation (typical RR 0.51, 95% CI 0.37,0.71) was significantly lower in treated infants. Prophylactic indomethacin also significantly reduced the incidence of severe intraventricular haemorrhage (typical RR 0.66, 95% CI 0.53 to 0.82). Meta-analyses found no evidence of an effect on mortality (typical RR 0.96, 95% CI 0.81 to 1.12) or on a composite of death or severe neurodevelopmental disability assessed at 18 to 36 months old (typical RR 1.02, 95% CI 0.90, 1.15).

AUTHORS' CONCLUSIONS

Prophylactic indomethacin has short-term benefits for preterm infants including a reduction in the incidence of symptomatic PDA, PDA surgical ligation, and severe intraventricular haemorrhage. However, there is no evidence of effect on mortality or neurodevelopment.

Treatment of persistent patent ductus arteriosus in preterm infants: time to accept the null hypothesis?

Medical and surgical interventions are widely used to close a persistently patent ductus arteriosus in preterm infants. Objective evidence to support these practices is lacking, causing some to question their usage. Emerging evidence suggests that treatments that close the patent ductus may be detrimental. This review examines the history of and evidence underlying these treatments. Neither individual trials, pooled data from groups of randomized-controlled trials, nor critical examination of the immediate consequences of treatment provide evidence that medical or surgical closure of the ductus is beneficial in preterm infants. These conclusions are supported by sufficient evidence. Neither continued routine use of these treatments nor additional clinical trials using similar designs seems to be justified. A definitive trial, comparing current standard management with novel strategies not primarily intended to achieve ductal closure, may be necessary to resolve doubts regarding the quality or conduct of prior studies.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. Prolonging the course of indomethacin has the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine the effect of a prolonged course of indomethacin (compared to a short course) on the rate of treatment failure without unwanted side-effects in preterm infants with PDA.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to December 2006), EMBASE (1974 to December 2006), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials including preterm infants with PDA, diagnosed on clinical and/or echocardiographic examination that evaluated indomethacin treatment by any route given as a long course (four or more doses) vs. a short course (three or fewer doses) were included in the review. Trials needed to report on at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three review authors independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. The I squared statistic was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Five trials met inclusion criteria and included 431 infants. Prolonged indomethacin treatment when compared to the short course did not result in a statistically significant difference in PDA closure, re-treatment, re-opening, or ligation rates. The prolonged course was associated with an increased risk of NEC [typical RR 1.87 (95% CI 1.07, 3.27); typical RD 0.08 (95% CI 0.01, 0.15); NNH 13 (7, 100)] and a decreased incidence of renal function impairment, as evidenced by a lower proportion of infants having diminished urine output [typical RR 0.27 (95% CI 0.13, 0.6); typical RD -0.19 (95% CI -0.28, -0.09); NNT 5 (4, 11)] and increased serum creatinine level [typical RR 0.51 (95% CI 0.33, 0.77); typical RD -0.14 (95% CI -0.23, -0.06); NNT 7 (4, 16)].

AUTHORS' CONCLUSIONS

Implications for practiceProlonged indomethacin course does not appear to have a significant effect on improving important outcomes, such as PDA treatment failure, CLD, IVH, or mortality. The reduction of transient renal impairment does not outweigh the increased risk of NEC associated with the prolonged course. Based on these results, a prolonged course of indomethacin cannot be recommended for the routine treatment of PDA in preterm infants. Implications for researchThere is a paucity of data on optimal dosing and duration of indomethacin therapy for the treatment of PDA, in particular for extremely low birth weight infants (ELBW) premature infants. It is likely that a single standard indomethacin regime is not the ideal for every premature infant. Therefore, individual patient response should be considered and evaluated, in particular in ELBW infants. Future randomized clinical trials should include this high risk population and investigate the effect of tailoring dose and duration of therapy to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes, including long-term neurodevelopmental outcomes. In addition, factors that may influence treatment effect, such as birth weight, gestational age, age at the time of randomization, total fluid intake, feeding practice, and severity of PDA, need to be taken into account when designing such studies.

Indomethacin use for the management of patent ductus arteriosus in preterms: a web-based survey of practice attitudes among neonatal fellowship program directors in the United States

The objective of this study was to determine whether neonatal-perinatal fellowship programs (NFTPs) in the United States vary in indomethacin use for the management of patent ductus arteriosus (PDA) in < or =28 week gestational age infants at birth. A 53-item web-based survey was sent to 84 NFTP directors who received prenotification, followed 2 weeks later by a reminder letter. A total of 56 NFTP directors responded (67% maximum response rate). Wide variation exists in the maximum number of indomethacin courses used to close ductus, use of indomethacin for reopened PDA beyond 14 days, ductal closure definition, contraindications before consideration of indomethacin, interventions for contraindications, and reported ductal closer rate after each indomethacin course. Indomethacin therapy for symptomatic PDA and short course of indomethacin are common practices. Indomethacin use for the management of PDA in premature infants varies among NFTP directors. Practice attitudes may explain variations in ductal closure and ligation rates. Because practice variations may have implications for long-term outcome of vulnerable premature infants, studies relevant to the management of PDA in premature infants are needed.

Effectiveness and side effects of an escalating, stepwise approach to indomethacin treatment for symptomatic patent ductus arteriosus in premature infants below 33 weeks of gestation

OBJECTIVE

Symptomatic patent ductus arteriosus (sPDA) is a common problem in premature infants and can be treated effectively with intravenous indomethacin, leading to permanent ductal closure in 70% to 80% of infants. Infants who do not respond to pharmacologic closure of the duct ultimately have to undergo surgical or interventional closure of the PDA. Optimizing the pharmacologic treatment could offer an interesting approach to reduce the number of infants who need surgical closure of the duct.

METHODS

We conducted a retrospective analysis in infants who were <33 weeks' gestation, had sPDA, and were treated with high-dose intravenous indomethacin. From 1993 to 2002, 129 infants with sPDA received indomethacin after diagnosis of sPDA was confirmed by echocardiography. Treatment was started in all infants with intravenous indomethacin (0.2 mg/kg given 5 times at 0 hours, 12 hours, 24 hours, 48 hours, and 72 hours). When the ductus was still open at 36 hours, indomethacin every 12 hours was continued and single doses increased up to 1 mg/kg until ductal closure was achieved.

RESULTS

In 68 (53%) of 129 infants who were treated with indomethacin, ductal closure occurred during intermediate-dose indomethacin therapy (up to 1.5 mg/kg total dose). In the 61 initial nonresponders, the continuation of indomethacin led to ductal closure in 59 infants. When infants who were treated with an intermediate dose were compared with the initial nonresponders, no differences in the incidences of renal or electrolyte abnormalities, gastrointestinal bleeding, intraventricular hemorrhage, or periventricular leukomalacia were found.

CONCLUSIONS

High-dose indomethacin after intermediate-dose therapy resulted in an overall closure rate of 98.5% (127 of 129). Although single indomethacin doses of up to 1 mg/kg were given, high-dose indomethacin was safe.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. A more prolonged course of indomethacin has been studied regarding the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine if a prolonged course of indomethacin (compared to a short course) reduces the rate of treatment failure in preterm infants with PDA without unwanted side-effects.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to April 2003), EMBASE (1974 to April 2003), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2003). No language restrictions were applied.

SELECTION CRITERIA

1) DESIGN AND POPULATION: Randomized or quasi-randomized controlled trials including preterm infants with PDA diagnosed on clinical and/or echocardiographic examination.2) INTERVENTION: Indomethacin treatment by any route given as a long course (four or more doses) vs a short course (three or fewer doses). 3) OUTCOMES: Report of at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three reviewers independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. A chi-square test was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Prolonged indomethacin treatment when compared to the short course resulted in a borderline statistically significant difference in PDA re-opening rate favoring the prolonged course [RR 0.54 (95% CI 0.3, 0.99); RD -0.12 (95% CI -0.24, -0.01); NNT = 8 (4, 100). There was no statistically significant treatment effect on PDA closure, re-treatment, or ligation rates. The prolonged course was associated with a decreased incidence of severe IVH [RR 0.49 (95% CI 0.25, 0.98); RD -0.12 (95% CI -0.24, -0.01); NNT 8 (4, 100)] and renal function impairment, as evidenced by a lower proportion of infants having an increased creatinine level [RR 0.52 (95% CI 0.34, 0.81); RD -0.20 (95% CI -0.33, -0.08); NNT 5 (3, 13)]. However, there was a trend for the prolonged course to increase the proportion of infants with CLD in the one trial reporting this outcome [RR 2.24 (95% CI 0.98, 5.12); RD 0.24 (95% CI 0.01, 0.47)].

IMPLICATIONS FOR PRACTICE

Prolonged as compared to short course of indomethacin for the treatment of PDA in preterm infants has a borderline effect on reducing the rate of PDA re-opening and it may be associated with an increased risk for CLD. However, prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in this population. Definitive recommendations about the preferred duration of indomethacin therapy, i.e. prolonged versus short course, for the treatment of PDA in premature infants cannot be made based on the current findings of this review.

IMPLICATIONS FOR RESEARCH

There is a paucity of data on optimal duration of indomethacin therapy for the treatment of PDA, in particular for ELBW premature infants. Future randomized clinical trials should include this high risk population and investigate the premature infants. Future randomized clinical trials should include this high risk population and investigate the possibility of tailoring duration of therapy (prolonged versus short) to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes and potential complications associated with either strategy. In addition, factors which may influence treatment effect need to be taken into account when designing such studies.

Factors associated with permanent closure of the ductus arteriosus: a role for prolonged indomethacin therapy

BACKGROUND

The most important factor determining anatomic remodeling and permanent closure of the ductus arteriosus is the degree of ductus constriction after indomethacin treatment. Muscular constriction produces a region of ischemic hypoxia in the middle of the ductus muscle media that initiates the process of permanent closure. Previous studies have shown that infants delivered before 28 weeks' gestation, who still have evidence of ductus flow on Doppler examination (performed after the standard 3-dose course of indomethacin), have a high likelihood (>85% chance) of reopening their ductus in the future. In contrast, if there is no evidence of luminal patency on the posttreatment Doppler examination, the incidence of ductus reopening is <20%. In the following study, we examined infants who still had a patent ductus on Doppler examination after a 3-dose course of indomethacin, to identify which factors might be associated with permanent ductus closure. We hypothesized that infants who received additional doses of indomethacin after the standard 3-dose course might develop an even tighter degree of ductus constriction and increase their chance of developing permanent closure.

METHODS

We performed a retrospective cohort study of preterm infants (< or =26; weeks' gestation) who were treated with indomethacin. Between 12 and 24 hours after the third dose of indomethacin, infants were examined for the presence or absence of ductus-related signs, and an echocardiogram was performed. Infants responded to the initial 3 doses of indomethacin in 1 of 3 ways: 1) the ductus was closed clinically (absent clinical signs) with no evidence of luminal flow on Doppler examination ("clinically closed"; n = 214); 2) the ductus was closed clinically, but a small amount of left-to-right luminal flow was evident on Doppler examination ("partially closed"; n = 69); 3) or the ductus was open clinically and echocardiographically ("nonresponder"; n = 30). Nonresponders underwent surgical ligation (n = 30). Infants with a partially closed ductus formed our study population. We used a hierarchical regression model to identify which, if any, of the following factors might be associated with permanent anatomic closure in the 69 infants with a partially closed ductus: 1) gestational age, 2) exposure to antenatal steroids, 3) birth weight, 4) sex, 5) presence and severity of respiratory distress, 6) fluid administration during the first 96 hours after birth, 7) indomethacin treatment approach (prophylactic vs symptomatic), 8) year of birth, 9) use of surfactant, 10) preeclampsia, 11) chorioamnionitis, 12) bacterial septicemia, 13) necrotizing enterocolitis, or 14) duration of indomethacin treatment (standard 3-dose course vs prolonged 6-dose course). Infants who received the standard 3-dose course of indomethacin treatment were given 0.2, 0.1, and 0.1 mg/kg indomethacin during a 48-hour period. Infants who received the prolonged 6-dose course of indomethacin treatment were given a fourth, fifth, and sixth dose of 0.1 mg/kg at 24 hour-intervals, starting 24 hours after the third dose.

RESULTS

Sixty-eight of the 69 infants survived long enough to complete all of the study evaluations. Seventy-five percent (51/68) reopened their ductus and became symptomatic; 71% (48/68) were eventually ligated. Only gestational age and duration of indomethacin treatment were significantly and independently associated with permanent closure. A prolonged 6-dose course of indomethacin was more likely than the standard 3-dose course to be associated with an increased incidence of echocardiographic closure, a decreased incidence of symptomatic reopening (odds ratio: 0.19; 95% confidence interval: 0.04-0.96), and a decreased incidence of ductus ligation (odds ratio: 0.14; 95% confidence interval: 0.03-0.68).

DISCUSSION

Several older studies have suggested that a longer initial course of indomethacin therapy may be more effective in producing permanent ductus closure than the standard 3-dose course. In contrast, more recent studies have found that a longer course of indomethacin is no more effective than the standard 3-dose course in producing permanent closure. We hypothesize that the different outcomes among these studies may be attributable to differences in the degree of ductus constriction during the standard 3-dose course of indomethacin. Both the increased use of antenatal steroids and the earlier use of indomethacin has increased the effectiveness of the standard 3-dose course of indomethacin in recent years. We hypothesize that, in contrast with earlier studies, a significant proportion of the infants in the recent studies may have developed complete Doppler closure with just 3 doses of indomethacin (as occurred in 214 of the 313 infants treated with the standard 3-dose course in our study). Because the degree of ductus constriction seems to determine the rate of anatomic remodeling and permanent closure, daily echocardiographic evaluations of ductal patency may be the best way to decide when indomethacin therapy is no longer needed. Our study suggests that infants who still have evidence of luminal patency, after a standard 3-dose course of indomethacin, may be likely to benefit from a longer course of indomethacin. Future randomized trials that examine the benefits of different lengths of indomethacin treatment may wish to take this into consideration.

CONCLUSIONS

Despite the increased effectiveness of a prolonged course of indomethacin, the rates of ductus reopening and surgical ligation were still very high in infants with a partially closed ductus. Other therapeutic approaches will need to be developed before permanent closure is likely to occur in this group of immature infants.

Comparative tolerability of pharmacological treatments for patent ductus arteriosus

The ductus arteriosus is a vascular channel which, although vital to the fetal circulation, rapidly becomes unnecessary and even deleterious after birth. As such, it is 'preprogrammed' to constrict within the first few hours of life. In infants born prematurely this natural closure is often delayed and/or ineffective. In this review, we summarise the current knowledge of the delicately orchestrated control of normal ductal closure, with emphasis on the role of various biochemical mediators. The major focus of this review, however, is on pharmacological approaches designed to prevent and/or treat the persistently patent ductus arteriosus (PDA) which often fails to constrict spontaneously in the premature infant. The standard treatment regimen is based on the administration of 3 doses of the nonselective cyclo-oxygenase inhibitor, indomethacin. We begin by examining, from the vantage point of the ductus, the use of this indomethacin as a tocolytic. It seems that antenatal administration of indomethacin can cause transient, reversible ductus constriction which renders the post-treatment ductus resistant to subsequent closure, both natural and therapeutic. We then review some of the pros and cons associated with the prophylactic administration of indomethacin. Although prophylactic indomethacin is aimed primarily at preventing intraventricular haemorrhages in premature neonates, it does tend to reduce the risk of PDA as well. We then describe some novel therapeutic approaches to effect ductal closure with indomethacin, including the use of continuous infusions to minimise toxic vasoconstrictive phenomena and the use of prolonged maintenance dose to prevent PDA recurrences. Finally we discuss some of the newer agents described more recently which play a role in closing the persistently patent ductus over the next decade. Most prominent of these is ibuprofen which some studies have shown to have less undesirable vasoconstrictive adverse effects. Studies which compare the use of ibuprofen to indomethacin are summarised.

Intravenous indomethacin for preventing mortality and morbidity in very low birth weight infants

BACKGROUND

This section is under preparation and will be included in the next issue.

OBJECTIVES

Indomethacin is used to treat symptomatic patent ductus arteriosus and may prevent or limit intraventricular haemorrhage in the neonatal period. This review examines the effectiveness of prophylactic intravenous indomethacin in reducing the mortality and morbidity associated with these conditions in infants weighing less than 1750 grams at birth.

SEARCH STRATEGY

A literature search from January 1980 to October 1994 was made in three computerised data bases: Medline; Embase; and the Oxford Database of Perinatal Trials. The search was updated in February 1997.

SELECTION CRITERIA

Strict selection criteria were applied to clinical trials: the population had to be newborn infants of birth weight < 1751 grams; the intervention had to be prophylactic intravenous indomethacin; the trial had to be randomised and controlled; and at least one of several prespecified outcomes had to be reported in the results.

DATA COLLECTION AND ANALYSIS

The methodological quality of each study was assessed using explicit criteria. Data on relevant outcome measures were extracted on two separate occasions and, where appropriate, the results of individual trials were combined using meta-analysis techniques to provide a pooled estimate of effect.

MAIN RESULTS

There is a trend towards reduced neonatal mortality in infants receiving prophylactic indomethacin, pooled relative risk (RR) = 0. 85 [95% CI 0.66 to 1.09]. The incidence of symptomatic patent ductus arteriosus is significantly reduced in treated infants, pooled RR = 0.35 [0.26 to 0.47] but there is no evidence that treatment affects respiratory outcomes. Prophylactic indomethacin significantly reduces the incidence of Grade 3 and 4 intraventricular haemorrhage in treated infants, pooled RR = 0.60 [0.43 to 0.83]. There is no evidence to suggest prophylactic indomethacin is associated with any long term adverse effect although there is a trend in treated infants towards an increased incidence of necrotizing enterocolitis, and some evidence that treatment may transiently impair renal function. There is no evidence that haemostasis is disturbed.

REVIEWER'S CONCLUSIONS

Prophylactic treatment with indomethacin has a number of immediate benefits, in particular a reduction in symptomatic patent ductus arteriosus and severe intraventricular haemorrhage. There is no evidence at present of long-term harm. Further trials are needed to assess more precisely the effects, both beneficial and harmful, on short and long-term outcomes.

Short versus prolonged indomethacin therapy for patent ductus arteriosus in preterm infants

OBJECTIVE

To evaluate whether a prolonged low-dose course of indomethacin would produce an improved closure rate and have fewer side effects compared with a short standard dosage schedule in the management of patent ductus arteriosus (PDA) in preterm infants.

STUDY DESIGN

Sixty-one infants of gestational ages 24 to 32 weeks with a PDA confirmed with echocardiography were randomized to receive 0.2 to 0.1 to 0.1 mg/kg indomethacin in 24 hours (short course, n = 31) or 0.1 mg/kg every 24 hours 7 times (long course, n = 30). Echocardiography was done 3, 9, and 14 days after the treatment was started, and side effects were monitored.

RESULTS

Primary PDA closure occurred more often in the short course group (94% vs 67%, P =.011), but the sustained closure rates were not different (74% vs 60%). Surgical PDA ligations were less frequent in the short course group than in the long course group. The short course group had a shorter duration of oxygen supplementation, less frequent symptoms of necrotizing enterocolitis, and a lower rate of urea retention. Mortality and other neonatal morbidity rates were similar.

CONCLUSION

A prolonged low-dosage indomethacin regimen offers no advantage compared with a standard-dosage short course in the management of a hemodynamically significant PDA in preterm infants.

Prolonged low dose indomethacin for persistent ductus arteriosus of prematurity

A total of 121 infants who required indomethacin for persistent ductus arteriosus in Liverpool and Cambridge over a four year period were randomised to receive either 0.1 mg/kg daily for six days or 0.2 mg/kg every 12 hours for three doses. The groups were of similar birth weight and gestational and postnatal age, though those treated with a low dose were by chance receiving a higher percentage of oxygen at the start of treatment and there were more deaths from bronchopulmonary dysplasia in this group. Of 59 infants treated with the prolonged course 53 (90%) responded initially to indomethacin compared with 48 of 62 (77%) treated conventionally--a difference of 13% (95% confidence interval for the difference 0 to 26%). Of the 53 responders 11 (21%) relapsed after low dose indomethacin, whereas after the shorter course 19 of 48 (40%) relapsed. This difference was significant (95% confidence intervals 3 to 37%). Side effects, mainly gastrointestinal haemorrhage, were similar in both groups. Significantly fewer infants experienced a rise in serum creatinine or urea concentration after treatment with low dose indomethacin. A prolonged low dose course of indomethacin offers advantages over conventional treatment.

Prolonged indomethacin therapy for the prevention of recurrences of patent ductus arteriosus

We tested the hypothesis that prolonged maintenance indomethacin therapy would allow more effective closure of patent ductus arteriosus (PDA) and thereby decrease the recurrence rate. Thirty-nine low birthweight neonates (less than 1500 gm) with confirmed PDA were randomly assigned in a double-blind fashion to receive standard indomethacin therapy (three doses), followed either by maintenance indomethacin therapy (0.2 mg/kg/day) for 5 days or by an equivalent volume of placebo for 5 days. Of the 20 infants who received maintenance indomethacin therapy, two (10%) required additional therapy and one of these required surgical ligation. Of the 19 infants who received only the first three indomethacin doses, nine (47%) required additional therapy for PDA (p less than 0.05) and seven of these had a ligation (p less than 0.05). We conclude that maintenance indomethacin therapy, in comparison with short-term indomethacin therapy, decreases the incidence of surgical PDA ligations, eliminates most PDA recurrences, and does not increase toxic effects of indomethacin in the low birth weight infant with PDA.

Pharmacokinetics of intra-arterial indomethacin treatment for patent ductus arteriosus

We present pharmacokinetic data of prolonged, intra-arterial indomethacin treatment (i.e. induction plus maintenance dose) for symptomatic patent ductus arteriosus (sPDA) in 26 ventilated premature infants. sPDA was assessed by two-dimensional and pulsed Doppler echocardiography. Permanent ductal closure occurred in 20 (76%) infants. Plasma levels of indomethacin were 1.18 +/- 0.74; 1.8 +/- 1.0; 1.51 +/- 0.93 and 1.25 +/- 0.98 micrograms/ml (mean +/- SD) at 12, 24, 48 and 72 h after initial dose administration. All except one patient who responded with ductal closure, showed plasma levels above 0.25 microgram/ml throughout the 3 day treatment period and no case of sPDA reopening was noted. Although target concentrations over time were not defined, the data indicate that the maintenance levels measured were within the therapeutic range. A negative correlation was found for plasma drug levels and postnatal age (r = 0.52; P less than 0.01). Volume of drug distribution was 0.23 +/- 0.18 l/kg, total clearance 0.1 +/- 0.11 ml/min and elimination constant 0.06 +/- 0.05 h-1 (mean +/- SD). The great variation in pharmacokinetic data reflects the heterogeneity of the population studied with respect to extracellular fluid space, cardiovascular status, serum protein and other parameters.