Epidemiological studies have documented a high prevalence of comorbid conditions among patients who have chronic obstructive pulmonary disease (COPD), including hypertension, ischemic heart disease, hypercholesterolemia, diabetes, and anxiety and depression (Barr RG et al. Am J Med 2009; Carrasco-Garrido P et al. BMC Pulm Med 2009; Finkelstein J et al. Int J COPD 2009). The epidemiological data underscore the need to know whether clinical trial results have come from studies that adequately represent the comorbidities of COPD patients.

To examine comorbidities in clinical trials of tiotropium, Marc Miravitlles, MD, Ciber de Enfermedades Respiratorias, Barcelona, Spain, and colleagues analyzed data from 26 placebo-controlled clinical trials that were at least 4 weeks in duration. Baseline evaluation included documentation of patients' concomitant diseases and relevant medical history of the previous 5 years.

The analysis comprised 17,014 patients with COPD whose mean age was 64.6 years. The data showed that 76% of the patients were men, 84.4% was Caucasian, and baseline mean forced expiratory volume in one second (FEV₁) was 41% of predicted.

Information on baseline comorbid conditions was available for 15,375 patients. Overall, 90.4% of the patients had concomitant diseases at baseline.

The most frequently cited categories of comorbid conditions were vascular disorders (44.0%), musculoskeletal and connective tissue disorders (35.2%), gastrointestinal disorders (32.6%), metabolism and nutrition disorders (28.8%), dyslipidemia (16.7%), diabetes (9.8%), and anxiety or depression (13.7%).

Because COPD and cardiovascular conditions frequently occur together, the investigators analyzed the data for specific references to individual disorders within the broader category of cardiovascular disease. They found that 38.7% of patients had hypertension, 15.6% had conditions that were suggestive of ischemic heart disease, and 16.7% had hypercholesterolemia or hyperlipidemia. With the exception of lipid and cholesterol abnormalities, the comorbidities of patients in the tiotropium clinical trials had prevalences that were similar to those of previous epidemiological studies, investigators concluded. Epidemiological data have generally shown higher rates of hypercholesterolemia or hyperlipidemia among patients with COPD.