Pregnancy is rare among breastfeeding women with lactational amenorrhoea. The lactational amenorrhoea method (LAM) is the informed use of breastfeeding as a contraceptive method by a woman who is still amenorrhoeic, and who is not feeding her baby with supplements, for up to 6 months after delivery. Under these three conditions, LAM users are thought to have 98% protection from pregnancy. It can be difficult, however, to determine when supplementation of the baby's diet begins. We have analysed data from nine studies of the recovery of fertility in breastfeeding women to assess the effectiveness of lactational amenorrhoea alone, irrespective of whether supplements have been introduced, as a fertility regulation method post partum. Cumulative probabilities of ovulation during lactational amenorrhoea were 30.9 and 67.3 per 100 women at 6 and 12 months, respectively, compared with 27.2 at 6 months when all three criteria of the LAM were met. Cumulative pregnancy rates during lactational amenorrhoea were 2.9 and 5.9 per 100 women at 6 and 12 months, compared with 0.7 at 6 months for the LAM. The probability of pregnancy during lactational amenorrhoea calculated from these studies is similar to that of other modern contraceptive methods, and it seems reasonable for a woman to rely on lactational amenorrhoea without regard to whether she is fully or partly breastfeeding. So that amenorrhoea and fertility suppression can be maintained, counselling about good breastfeeding and weaning practices remains important.

The efficacy of azathioprine in the treatment of multiple sclerosis was assessed by meta-analysis of the results of all published blind, randomised, controlled trials. 793 patients were enrolled in 5 double-blind and 2 single-blind studies. After 1 year of treatment, the increase in Kurtzke disability status score was no different in treated and control groups, but at 2 years there was a small difference (-0.22; 95% confidence interval [CI] -0.43, 0.003) in favour of azathioprine treatment; this difference was sustained, but not increased, after 3 years. The probability of freedom from any relapse during 1, 2, and 3 years' treatment was significantly greater in the azathioprine-treated group (relative odds over 3 years 1.97; 95% Cl 1.27, 3.04), but it is debatable whether the slight clinical benefits of azathioprine outweigh its side-effects.

To assess the effect of selective decontamination of the digestive tract on respiratory tract infections and survival of patients treated in an intensive care unit, we carried out a meta-analysis of clinical studies comparing patients treated with selective decontamination with untreated controls. From eleven trials (1489 patients), differences between observed and expected respiratory tract infections and mortality were compared, and odds ratios (ORs) calculated. Analysis was done according to study design. With respect to the risk for respiratory tract infections, the studies with historical controls and the randomised trials showed a protective effect of selective decontamination. Historical control studies yielded an OR of 0.21 (95% confidence limits [CL] 0.15 to 0.29, p less than 0.05) and randomised trials an OR of 0.12 (95% CL 0.08 to 0.19, p less than 0.05). By contrast, the mortality benefit was less clear. Studies with historical controls and randomised trials showed that mortality was not significantly different between treatment and control patients. The evidence from these studies is at best consistent with a very limited effect of selective decontamination of the digestive tract on survival of patients in the intensive care unit, despite a clear preventive effect on the occurrence of respiratory tract infections.

A meta-analysis of all controlled clinical trials of beta-adrenoceptor blocking drugs, principally propranolol, in the prevention of primary or secondary variceal bleeding has shown that beta-blockade significantly reduced the occurrence of variceal bleeding, deaths from variceal bleeding, and overall mortality. There was some heterogeneity between trials in the effect of beta blockade on secondary prevention. When only fully reported, randomised, placebo-controlled studies were included the heterogeneity disappeared, and the reductions in bleeding episodes and mortality became more striking. Separate analyses of primary and secondary prevention studies also showed clear reductions in occurrence of variceal bleeding and deaths. These results seem to indicate the value of beta-adrenoreceptor blocking drugs for the primary prevention of haemorrhage from large oesophageal varices. However, there is still a need for large multicentre trials of beta-blockade for primary prevention of variceal bleeding in patients without large varices and of comparisons between beta-blocker therapy with other treatments in secondary prevention.

80 reports of randomised clinical trials in four leading general medical journals were reviewed. The reporting of the methodology of randomisation was inadequate. In 30% of trials there was no clear evidence that the groups had been randomised. Among trials that used simple randomisation the sample sizes in the two groups were too often similar, and there was an unexpected small bias in favour of there being fewer patients in the experimental group. The handling of comparisons of baseline characteristics was inadequate in 41% of the trials. Suggestions are made for improving standards.