Table 1

 Statistically significant differences in treatment effects in less developed countries versus more developed countries

TopicExperimental intervention*OutcomeSummary relative risks (95% CI)Relative relative risk (95% CI) for more v less developed countriesP values
Trials from more developed countries†Trials from less developed countries†Small study effectsDifferences in baseline risk
Antenatal prevention in preterm birth33CorticosteroidsFetal and neonatal deaths0.83 (0.68 to 1.02)0.40 (0.26 to 0.61)2.08 (1.30 to 3.33)0.103<0.001
Antioxidant supplements for prevention39AntioxidantsMortality‡1.06 (1.03 to 1.10)0.94 (0.85 to 1.05)1.13 (1.01 to 1.27)0.434<0.001
Multiple pregnancy42Admission to hospital for bed restPerinatal death3.15 (0.88 to 11.23)0.71 (0.35 to 1.46)4.42 (1.03 to 18.99)0.9510.21
Treatment of sepsis and septic shock34CorticosteroidsAll cause mortality at 28 days‡0.89 (0.74 to 1.08)0.35 (0.14 to 0.87)2.58 (1.01 to 6.63)0.03<0.001
Prevention of gastrointestinal cancers40AntioxidantsMortality1.07 (1.04 to 1.11)0.93 (0.84 to 1.04)1.15 (1.03 to 1.29)0.152<0.001
Non-neutropenic critically ill patients35Systemic antifungalsMortality‡0.76 (0.58 to 1.01)0.24 (0.08 to 0.68)3.18 (1.08 to 9.40)0.019<0.001
Treatment of non-small cell lung cancer41Postoperative radiotherapyMortality‡1.37 (1.12 to 1.68)0.85 (0.57 to 1.28)1.61 (1.03 to 2.53)0.7580.028
Aneurysmal subarachnoid haemorrhage36Calcium antagonists aloneCase fatality0.86 (0.64 to 1.13)0.15 (0.03 to 0.76)5.73 (1.13 to 28.3)0.3020.99
Prevention of infection in preterm or low birthweight infants37Intravenous immunoglobulinAll cause mortality0.95 (0.77 to 1.17)0.49 (0.27 to 0.91)1.93 (1.01 to 3.66)0.137<0.001
Unresectable hepatocellular carcinoma38Transarterial chemoembolisation or transarterial embolisationAll cause mortality‡0.88 (0.72 to 1.08)0.50 (0.31 to 0.81)1.76 (1.05 to 2.97)0.683NP
Oral cavity and oropharyngeal cancer43Altered fractionation radiotherapyTotal mortality‡0.91 (0.85 to 0.98)0.57 (0.37 to 0.88)1.60 (1.03 to 2.48)0.790NP
Cirrhosis with upper gastrointestinal bleeding44AntibioticsBacterial infections‡0.30 (0.21 to 0.42)0.13 (0.07 to 0.25)2.30 (1.10 to 4.82)0.088<0.001
Peripheral arterial disease of leg45Lipid lowering regimensCardiovascular events‡0.77 (0.70 to 0.85)0.06 (0.01 to 0.46)13.28 (1.68 to 104.97)0.4110.081
Pneumococcal infection in adults46VaccinationAll cause pneumonia‡0.85 (0.77 to 0.95)0.52 (0.43 to 0.63)1.64 (1.32 to 2.03)0.864<0.001
Prevention of pre-eclampsia47AntioxidantsPre-eclampsia‡0.96 (0.80 to 1.16)0.38 (0.20 to 0.73)2.54 (1.29 to 5.01)0.0710.60
Vitamin E supplementation in pregnancy48Vitamin EClinical pre-eclampsia‡0.55 (0.30 to 1.01)0.06 (0.01 to 0.45)9.52 (1.11 to 81.74)0.8580.48
Prevention of gastrointestinal cancers40AntioxidantsIncidence of gastrointestinal cancers‡1.05 (0.97 to 1.14)0.86 (0.74 to 0.99)1.23 (1.04 to 1.45)0.004<0.001
Hypertension during pregnancy49β blockersCaesarean section‡1.03 (0.80 to 1.32)0.36 (0.17 to 0.77)2.83 (1.28 to 6.29)0.3020.37
Hepatic encephalopathy52ProbioticsNo recovery from hepatic encephalopathy‡0.03 (0.01 to 0.53)0.61 (0.32 to 1.18)0.04 (0.01 to 0.93)0.4290.09
Prevention of pre-eclampsia51Antiplatelet agentsProteinuric pre-eclampsia‡0.74 (0.65 to 0.86)0.93 (0.79 to 1.09)0.80 (0.65 to 0.99)<0.00010.13
Tuberculosis prevention in non-HIV infected people53IsoniazidActive tuberculosis‡0.34 (0.28 to 0.42)0.59 (0.40 to 0.86)0.58 (0.38 to 0.90)0.811<0.001
Prophylactic antifungal agents in very low birthweight infants54FluconazoleInvasive fungal infection‡0.23 (0.11 to 0.49)1.09 (0.48 to 2.48)0.21 (0.07 to 0.64)0.8330.07
Prevention of infection in preterm or low birthweight infants37Intravenous immunoglobulinSepsis‡0.89 (0.74 to 1.06)0.31 (0.16 to 0.62)2.84 (1.40 to 5.79)0.0590.99
Antenatal care for low risk pregnancy50Reduced number of visits or goal oriented visitsPreterm birth‡1.24 (1.01 to 1.52)0.99 (0.91 to 1.08)1.26 (1.01 to 1.57)0.787NP
Diarrhoea prevention55Rotavirus vaccineEpisodes of rotavirus diarrhoea‡0.48 (0.42 to 0.54)0.61 (0.52 to 0.72)0.78 (0.63 to 0.96)0.6110.006

NP=not pertinent because number of events in each arm was not available.

*In all cases, the experimental intervention has been compared with placebo or no treatment, except for surgery plus postoperative radiotherapy, which was compared against surgery alone; altered fractionation which was compared with conventional radiotherapy; reduced number of antenatal care visits or goal oriented visits, which were compared with standard care visits.

†Individual trial relative risks from trials within the same country group were combined with a fixed effect model.

‡The primary binary outcomes of the respective systematic reviews.