Does the sheer prevalence of lung diseases such as asthma and COPD lead to the overlooking of restrictive pulmonary defects?

Introduction: Use of spirometry enhances diagnostic accuracy. This report concerns one aspect of evaluation of the first 3.5 years of a community respiratory assessment unit. Methods Referral forms, nurses’ records and results of investigations of patients referred between 2005 and 2008 were examined. Where relevant, hospital and GP records were reviewed. Results: 84% (857/1024) of referrals attended. 6% (51/857) had spirometric evidence of a restrictive pulmonary defect (22M, 29F, age 63±15 years) (referral diagnoses: 26/51 suspected/definite COPD, 14/51 suspected/definite asthma, 11/51 unexplained breathless). 24/51 were obese (body mass index (BMI) >30) and a further 15/51 were overweight (BMI 25–30). In 10/51 cases no chest radiograph (CXR) was available. 5/10 of these had a BMI >30 and this was the likely cause of restriction. 41/51 patients had an available CXR. BMI >30 was the likely cause of restriction in 13/41, and the combination of BMI >30 with another cause in 6/41 (significant cardiac enlargement (n¿=¿3), pulmonary atelectasis (n¿=¿2), gastric pull-up surgery (n¿=¿1)). Overall, BMI >30 was the probable sole or a major contributory cause of restriction in 24/51(47%). Where BMI was