Meta-analysis of non-randomized Indian trials confirming results of a Cochrane systematic review based on randomized trials

Article type
Authors
Van Remoortel H1, De Buck E1, Vandekerckhove P1, Agarwal SP2
1Belgian Red Cross Flanders, Belgium
2Indian Red Cross, India
Abstract
Background:
New malaria cases in India are estimated at 24 million/year by the World Health Organization, resulting in a high socio-economic burden. A Cochrane systematic review, published in 2004, based on randomized controlled trials in non-Indian countries, showed that insecticide-treated bed nets (TN) are highly effective in reducing morbidity from malaria.

Objectives:
To investigate the effectiveness of TN on malaria in Indian families as part of the development of evidence-based Indian first aid and prevention guidelines.

Methods:
We performed a systematic literature review in MEDLINE and EMBASE to find Indian studies on the effectiveness of TN compared to untreated bed nets (UN) or no bed net (NN). Slide positivity rate (SPR; (total number of positive blood slides * 100)/total blood slides) served as malaria outcome. The overall effect of using TN compared to UN/NN on malaria (SPR) was investigated by grouping all studies in a meta-analysis and calculating the pooled risk ratios (RR).

Results:
We selected 32 references from 1602 relevant articles. Based on our selection criteria, we finally retained nine Indian non-randomized controlled clinical trials. Using TN decreased the risk of malaria in terms of SPR compared to UN (28% risk reduction, overall RR 0.72 (95%CI; 0.66 to 0.78)). This risk reduction was even doubled when comparing the use of TN with NN (56% risk reduction, overall RR 0.44 (95%CI; 0.41 to 0.48)). Quality of the evidence can be considered as moderate (level B according to GRADE) because of the non-randomized allocation procedure in all studies. The Cochrane systematic review revealed similar results by showing that TN reduced the incidence of uncomplicated malarial episodes by 39% compared to UN (three RCTs) and by 50% compared to NN (four RCTs).

Conclusions:
There is evidence from nine experimental Indian studies that using insecticide treated bed nets is an effective intervention to prevent malaria, which is in line with the findings of the Cochrane systematic review, performed outside India. The present findings support the current bed net use in the Vector-Borne Disease Control Project in India.