Evaluation of a meta-analysis of air quality and heart attacks, a case study.

It is generally acknowledged that claims from observational studies often fail to replicate. An exploratory study was undertaken to assess the reliability of base studies used in meta-analysis of short-term air quality-myocardial infarction risk and to judge the reliability of statistical evidence from meta-analysis that uses data from observational studies. A highly cited meta-analysis paper examining whether short-term air quality exposure triggers myocardial infarction was evaluated as a case study. The paper considered six air quality components - carbon monoxide, nitrogen dioxide, sulphur dioxide, particulate matter 10 µm and 2.5 µm in diameter (PM10 and PM2.5), and ozone. The number of possible questions and statistical models at issue in each of 34 base papers used were estimated and p-value plots for each of the air components were constructed to evaluate the effect heterogeneity of p-values used from the base papers. Analysis search spaces (number of statistical tests possible) in the base papers were large, median = 12,288 (interquartile range = 2496 - 58,368), in comparison to actual statistical test results presented. Statistical test results taken from the base papers may not provide unbiased measures of effect for meta-analysis. Shapes of p-value plots for the six air components were consistent with the possibility of analysis manipulation to obtain small p-values in several base papers. Results suggest the appearance of heterogeneous, researcher-generated p-values used in the meta-analysis rather than unbiased evidence of real effects for air quality. We conclude that this meta-analysis does not provide reliable evidence for an association of air quality components with myocardial risk.

A retrospective randomized study of asthma control in the US: results of the CHARIOT study.

BACKGROUND: The third version of the National Asthma Education and Prevention Program (NAEPP) Expert Panel Report (EPR-3): Guidelines on the Diagnosis and Management of Asthma emphasizes the need to use asthma control rather than patient severity to base adjustments to treatment and ultimately improve patient outcomes. The objectives of the current study were to assess control of patients with moderate-to-severe asthma, examine the natural history of the disease, practice patterns and resource utilization in specialty community practices according to recently reviewed NAEPP guidelines. RESEARCH DESIGN AND METHODS: This analysis represents a retrospective, multicenter, randomized study of 1009 patient charts in sixty United States allergy and pulmonary medicine community practices. The proportion of patients with controlled and uncontrolled asthma over 12 months, prevalence and characteristics of atopy, past asthma history, pulmonary function, medications and treatment patterns, patient and clinical practice characteristics were analyzed. MAIN OUTCOME MEASURES: The primary outcome of interest was asthma control. RESULTS: A total of 365 male and 644 female patients with moderate-to-severe persistent asthma (mean 43.2 +/- 17.1 years) were enrolled. 81.9% of patients were uncontrolled according to recent NAEPP guidelines. Importantly, a greater percentage of patients with moderate asthma vs. severe persistent asthma were uncontrolled (p < 0.0114). Atopy was detected in 92% of patients. Patients with early onset of asthma were associated with control (p < 0.0433). Atopic symptoms, such as allergic rhinitis (p < 0.0130) and rhinosinusitis (p < 0.0476), were associated with uncontrolled asthma. Uncontrolled patients were also associated with more medications (a mean of 4.05 +/- 1.87 medications) than were controlled patients (a mean of 3.40 +/- 1.37 medications (p < 0.0001), although the temporal relationship of this association was not recorded. Limitations may have included patient and/or study site selection bias and difficulty in the process of operationalizing the definitions of control and disease severity. Since the current study only examined patients from specialty practices, the results may not be generalizable to the overall asthma population. CONCLUSIONS: Greater than 80% of asthma patients from specialty practices were uncontrolled with regard to asthma symptoms. Atopic symptoms, such as allergic rhinitis and rhinosinusitis, in addition to a greater number of medications, were associated with uncontrolled asthma. Moreover, patients designated as having asthma of moderate severity were associated with being uncontrolled more than were those with severe asthma (p < 0.0114), which suggests that the former population may not have received adequate assessment of impairment or risk, with subsequent changes in treatment for control of symptoms.