Importance of Systematic Reviews and Meta-analyses for Research and Practice

Public health interventions are conventionally cited as a popular example of complex interventions. Complexity of public health interventions has always been an obstacle for the meta-analysis of these studies. Earlier an attempt was made by Public Health Evidence South Asia (PHESA) to numerically measure the complexity in public health interventions by a tool. This study is an extension of that initiative which aims to investigate various statistical distributional properties of the complexity score and adjust the measured complexity in meta-analysis.

Complexity score of 71 studies was used to identify the best probability distribution that fits the complexity score, study its sampling distribution and determine the optimum power transformation. Meta-regression was employed to adjust the measured complexity in meta-analysis.

Lognormal distribution was observed to be an ideal probability distribution for the complexity score, the sampling distribution of the mean of complexity score was found to be normally distributed and the optimum power transformation for the complexity score was ‘−0.42’. The raw estimate from random effects meta-analysis was found to be −0.05, 95% CI −0.14 to 0.04, whereas the estimate adjusted for complexity from meta-regression was −0.048, 95% CI −0.13 to 0.03. There was a reduction in the proportion of heterogeneity (I – squared) after adjusting for complexity (73.01%–66.30%), indicating that complexity had an impact on the effect estimates of studies.

The concept of measuring the inherent complexity and adjusting it in meta-analysis adds novelty to the existing meta-analysis approach. This innovative approach is likely to create a new dimension for meta-analysis of complex community level interventions and provide more precise evidence. However, further methodological research and piloting is required to establish the validity and sensitivity of this approach.

Injuries are the leading cause of morbidity and mortality confronting U.S. military forces in peacetime or combat operations. Not only are injuries the biggest health problem of the military services, they are also a complex problem. The leading causes of deaths are different from those that result in hospitalization, which are different from those that result in outpatient care. As a consequence, it is not possible to focus on just one level of injury severity if the impact of injuries on military personnel is to be reduced. To effectively reduce the impact of a problem as big and complex as injuries requires a systematic approach.

The purpose of this paper is to: (1) review the steps of the public health process for injury prevention; (2) review literature on evaluation of the scientific quality and consistency of information needed to make decisions about prevention policies, programs, and interventions; and (3) summarize criteria for setting objective injury prevention priorities. The review of these topics will serve as a foundation for making recommendations to enhance the effectiveness of injury prevention efforts in the military and similarly large communities. This paper also serves as an introduction to the other articles in this supplement to the American Journal of Preventive Medicine that illustrate the recommended systematic approach.