The authors concluded that additional benefits for intrauterine insemination compared with timed intercourse controls were not significant, but pregnancy rates might have been lower in intercourse compared with expectant management controls. These conclusions appear to be appropriately cautious, but incomplete reporting of review methods and limitations of treatment comparison methods make it difficult to assess their reliability.

To compare intrauterine insemination using male partner’s prepared semen with timed intercourse and expectant management controls, in infertile couples, and hence to determine the influence of control treatment on intrauterine insemination benefits.

MEDLINE, EMBASE, the Cochrane Menstrual Disorders and Subfertility Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), the ISRCTN Register, abstracts of the American Society for Reproductive Medicine and the European Society of Human Reproduction and Embryology annual meetings (1998 to 2007), and reference lists of six previous meta-analyses and identified studies, were searched up to February 2008. Search terms were reported and no language restrictions were applied. Studies reported only as abstracts were eligible.

Randomised controlled trials (RCTs) were eligible for inclusion if they compared intrauterine insemination with timed intercourse and reported sufficient data on pregnancy or live birth rates per couple to allow the creation of two-by-two tables. Trials had to use equivalent cointerventions in all treatment groups, be truly randomised, and have outcome data available for the first phase of crossover trials.

Some trials used cointerventions with clomiphene citrate or gonadotrophins. The two with expectant management as the control did not use cointerventions. Most of the trials included couples with unexplained infertility.

Two reviewers independently selected studies and resolved minor disagreements with the help of a third reviewer.

For inclusion, trials had to meet minimum validity criteria for randomisation and comparable cointervention. Blinding and allocation concealment were also assessed.

The authors did not state how many reviewers assessed validity.

For each study, numbers of pregnancies or births were extracted and used to create two-by-two tables, from which event rates were calculated.

The authors did not state how many reviewers performed the data extraction.

Pooled differences in pregnancy rates per couple were calculated using fixed-effect and random-effects models, but only the results from random-effects models were reported. Trials were weighted by the inverse variance and heterogeneity was assessed using the Q and the I² statistics. The influence of the following factors was examined: type of control; diagnosis of unexplained infertility or male factor; and use of clomiphene citrate or gonadotrophins. Sensitivity analysis was undertaken by including previously excluded trials and by removing outlier trials. Adjusted indirect comparisons were used to estimate the difference in pregnancy rate between timed intercourse and expectant management. Publication bias was assessed using a funnel plot and tested using the rank correlation test of Begg and Mazumdar.

Eleven RCTs were included (n=1,279 couples). Seven were parallel-group trials, three were crossover trials, and one was a Latin square trial. Five reported the methods of randomisation and five reported adequate methods of allocation concealment. None of the trials were blinded.

For all trials, the difference in pregnancy rate between intrauterine insemination and control ranged from -22.4% to 23.8%. Insemination was associated with a non-statistically significant increase in pregnancy rate compared with control; rate difference 6% (95% CI -0.9 to 12.6). Significant heterogeneity was found (p=0.009). Heterogeneity was no longer significant for insemination versus control after omitting trials that used clomiphene as a cointervention; pooled rate difference 7.0% (95% CI -4.6 to 18.7; ten trials).

Insemination was associated with a non-statistically significant increase in pregnancy rate compared with timed intercourse; pooled rate difference 6.1% (95% CI -2.2 to 14.6; nine trials). Insemination was associated with a significant increase in pregnancy rate compared with expectant management; pooled rate difference 3.9% (95% CI 2.8 to 4.7; two trials). There was no significant heterogeneity between groups (p=0.82).

Adjusted indirect comparisons showed no statistically significant difference in pregnancy rate between timed intercourse and expectant management; pooled rate difference 2.2% (95% CI -6.3 to 10.7).

Results for sensitivity analyses were similar and no significant publication bias was found (p=0.54).

The additional benefit for intrauterine insemination compared with intercourse controls was not significant, and pregnancy might have been less likely in intercourse controls than in expectant management controls.

The review question was clearly stated and inclusion criteria were defined for intervention, participants, outcomes, and study design. Several relevant sources were searched and attempts were made to minimise publication and language bias. Methods were used to minimise reviewer errors and bias in the selection of trials, but it was not clear whether similar steps were taken for the assessment of validity or data extraction. Information such as the age of participants and the stage at which a diagnosis of pregnancy was accepted as a positive outcome would have been useful in assessing the comparability of trials. Validity was assessed, but the assessment appeared to be limited. Trials were combined using meta-analysis and various sensitivity and subgroup analyses were used to examine potential sources of heterogeneity. Expectant management and timed intercourse were compared using adjusted indirect comparisons.

The authors’ conclusions appear to be appropriately cautious, but concerns about incomplete reporting of review methods and study details and the use of indirect comparison methods to compare treatments make it difficult to assess their reliability.

The authors did not state any implications for practice or research.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.