ADULT-RESPIRATORY-DISTRESS-SYNDROME - A SYSTEMATIC OVERVIEW OF INCIDENCE AND RISK-FACTORS

Objective: To determine the published incidence of adult respiratory d istress syndrome (ARDS) as well as the clinical evidence supporting a causal association between ARDS and its major risk factors. Data Sourc es: The National Library of Medicine MEDLINE database and the bibliogr aphies of selected articles. Study Selection: Clinical studies were se lected from the English literature, if they pertained to either the in cidence of ARDS or its association with one or more commonly identifie d risk factors. Data Extraction: All relevant studies identified by th e search were evaluated for strength of design, and risk factors were scored according to established criteria for the strength of causation . Data Synthesis: A total of 83 articles were considered relevant: six on incidence and 77 on risk factors, Only 49% of the 83 articles prov ided a definition of ARDS; a definition of risk factors was given in 6 4%, and 23% had no definition for either ARDS or risk factors,The publ ished, population-based incidence of ARDS ranges from 1.5 to 5.3/10(5) population/yr. The strongest clinical evidence supporting a cause-eff ect relationship was identified for sepsis, aspiration, trauma, and mu ltiple transfusions. The weakest clinical evidence was identified for disseminated intravascular coagulation, The following study types were represented by the 77 articles on risk factors: observational case-se ries (56%); cohorts (23%); case-controls (12%); nonrandomized clinical trials (5%); and randomized clinical trials (3%), Only a single study reported an odds ratio. Conclusions: The significant variation in the incidence of ARDS is attributed to differences in the type and streng th of study designs, as well as definitions of ARDS, While a substanti al body of evidence exists concerning a causal role for ARDS risk fact ors, such as sepsis, aspiration, and trauma, >60% of clinical studies employed weak designs, The lack of reproducible definitions for ARDS o r its potential risk factors in 49% of studies raises concerns about t he validity of the conclusions of these studies regarding the associat ion between ARDS and the supposed risk factors.