Measurement of lung function through Pulmonary Function Tests(PFTs) provides an assessment of the severity of airflow limitation and information for management of asthma. Although PFT abnormalities are common among patients with increasing asthma severity, they can be affected by age, gender, ethnicity and BMI. This study is motivated by the scant literature that exists on PFT characteristics among inner city New Yorkers with asthma.
A retrospective study of all patients diagnosed with asthma and who underwent PFTs between 2002 to 2008 was conducted. Data regarding severity of asthma, demographics, tobacco use, and PFTs results were collected by an independent trained investigator. The diagnosis of asthma and PFT results were obtained from the pulmonary clinic charts. Severity of asthma was classified as intermittent, mild persistent, moderate persistent and severe persistent using standard guidelines. Using stepwise logistic regression, odds ratios were calculated and 95% confidence intervals were reported. A p-value < 0.05 was considered significant.
Among 1608 patients of clinical diagnosis of Bronchial Asthma, 79% were Hispanic with mean age 50 years (SD +/− 14). 75 % were noted to have abnormal PFTs. By asthma severity, 17.8% were intermittent, 21.2% mild persistent, 56.3% moderate persistent and 4.5% severe persistent. Normal and abnormal PFTs were proportionally distributed across the asthma sub-types along with clinical characteristics of patients, as shown in Table-1. In both univariate and multivariate analysis, female gender was significantly associated with lower odds of abnormal PFTs (OR 0.60, 95% CI 0.46 to 0.77, p < 0.000). Presence of PFT abnormalities however did not correlate with severity of asthma.
Women with asthma were more likely to have normal PFTs even after controlling for age, ethnicity, BMI and severity of asthma.
This is the largest reported database describing the characteristics of PFTs among inner city New Yorkers. Although PFTs are routinely used in the diagnosis and management of asthma, the presence of abnormalities on PFTs surprisingly did not correlate with the severity of bronchial asthma.
Raghu Loganathan, No Financial Disclosure Information; No Product/Research Disclosure Information