Study design and outcomes in out-of-hospital emergency medicine research: a ten-year analysis

Lack of rigorous study design and failure to follow diverse patient outcomes have been identified as critical gaps in the medical research literature. This study sought to determine whether similar gaps exist in the literature for out-of-hospital interventions.

A computerized MEDLINE search was conducted for the ten-year period 1985 through 1994 using the MeSH terms "emergency medical services," "prehospital," and "transportation of patients." Using a standard abstraction form, two investigators independently analyzed articles meeting these inclusion criteria: original research evaluating an out-of-hospital intervention and measuring a patient outcome. Study design was categorized in order of scientific rigor, moving from case series to randomized trial. Measures of outcomes were classified into the six Ds: death, disease, discomfort, disability, dissatisfaction, and debt (cost).

Interobserver agreement was high (kappa = 0.80). For the ten-year period, 3,686 titles, 1,454 abstracts, and 373 articles were examined serially; all 285 studies meeting inclusion criteria were analyzed. Case series (44%) was the most frequently used design, while only 15% were randomized trials. The majority of the studies were retrospective (53%). A single outcome was assessed in 45% of the articles; 41% measured two outcomes, 13% three outcomes, and 1% four outcomes. Death and disease were the most common outcomes evaluated. Disability, debt, discomfort, and dissatisfaction were infrequently measured.

Studies of out-of-hospital emergency medical interventions are limited in the scientific rigor of study design and the diversity of patient outcomes measured. To adequately assess the effectiveness of out-of-hospital care, efforts should be directed toward strengthening study designs and examining the full range of patient outcomes.