Prevalence of obstructive airway disease by spirometric indices in non-smoker subjects with IHD and HTN

Background: Recent studies have found that there is a strong association between ischemic heart disease (IHD) and hypertension (HTN) with spirometric indices.

Aims: To study the prevalence of obstructive airway disease (OAD) in non-smoker subjects with IHD and HTN and to compare them with healthy population.

Settings and design: This was a prospective, case-control, and observational study.

Subjects and methods: A total of 100 patients (cases) (n = 100) admitted in medicine department were recruited for this study. Controls (n = 100) were apparently healthy age- and sex-matched without HTN and IHD, recruited from March 2007 to July 2008. All eligible subjects were subjected to spirometric examination on a turbine-based spirometer (MIR spirolab-II) according to ATS/ERS guidelines. Forced expiratory volume/forced vital capacity (FEV(1)/FVC) ratio <70% was used to make a diagnosis of OAD.

Statistical analysis used: All analyses were carried out using Statistical Software Package for Social Sciences trial version (SPSS 10 version).

Results: Out of 100 cases, 18 were with FEV(1)/FVC ratio <70% (OAD) and 82 had >70% FEV(1)/FVC ratio. Out of 100 controls, 2 were with FEV(1)/FVC ratio <70% (OAD) and 98 had >70% FEV(1)/FVC ratio. Eleven patients out of 66 from the case population with HTN had FEV(1)/FVC ratio <70% (Odds ratio 8.044). Prevalence of OAD in the hypertensive individuals was 16.66%. Twelve patients out of 62 from the case population with IHD had FEV(1)/FVC ratio <70% (Odds ratio of 9.333). Prevalence of OAD in the IHD individuals was 19.35%. In multiple correlation results for case population, when pulmonary function test variables were correlated with various dependant (age) and independent variables [HTN, IHD, height, weight, body mass index (BMI)], they were significantly reduced (P = 0.00017). In multivariate analysis (MANOVA), spirometric variables like FEV(1), FEV(1)/FVC%, FVC, forced expiratory flow (FEF) 25-75%, and peak expiratory flow rate (PEFR) were compared with factors like IHD, HTN, and covariates like age and BMI. We found that systolic blood pressure (SBP; P = 0.005), diastolic blood pressure (DBP; P = 0.05), height (P = 0.05), weight (P = 0.042), and IHD (P = 0.0001) were strongly associated with reduced pulmonary functions like FEV(1), FEV(1)/FVC%, and FVC. The presence of IHD and HTN were independently associated with the presence of OAD.

Conclusions: This study highlights the increased prevalence of OAD amongst patients with IHD and HTN. Patients with IHD and HTN should routinely undergo inexpensive investigations like spirometry to detect the presence of underlying OAD.