PURPOSE: The objective of the study was to determine the association of body mass index (BMI) to the diagnosis of asthma.
METHODS: We did a consecutive case analysis of 20 patients diagnosed with asthma on clinical bases but none of them fit the criteria of having FEV1/FVC ratio less than 70%. Data collected included demographic information, co morbid condition, smoking history and body mass index. Calculated Body Mass Index was as follows: BMI 18.5 –24.9 was NL (n= 2), BMI 25.0 –29.9 was overweight (n= 4), BMI 30 –34.9 was obese ation (n= 9), and BMI >35 was morbidly obese (n= 5). All patients who had FEV1/FVC % ratio of > 70 and were still suspected to have asthma, subsequently underwent a bronchoprovocation testing with methacholine to determine bronchial responsiveness. Rosenthal dosage protocol for methacholine was administered with maximum PC20 concentration of 25mg/ml. Saline was used as baseline Stage 0, then escalating doses of methacholine was used; Stage 1 (.025 mg/ml), Stage 2 (0.25mg/ml), Stage 3 (2.5mg/ml), Stage 4 (10mg/ml) and Stage 5 (25mg/ml). Responsiveness to Methacholine was differentiated into three Groups. Group 1 (Hyper-responsiveness) included stages 1-3, Group 2 (Reactive) included stage 4 and Group 3 (Non-reactive) included stage 5 and 6.
RESULTS: After reviewing the cases of 20 patients only 2/20 (10%) were in Normal BMI range, 4/20 (20%) overweight, 9/20 (45%) obese, and 5/20 (25%) in morbid obese category. Note that 90% (18/20) of the patients were above the normal BMI and had the diagnosis of Asthma. Out of the 90% who were above normal BMI 4/18 were in Group 1, 3/18 were in Group 2 and 11/18 were in Group 3. Group 1 and 2 were considered positive 7/18 (39%) and Group 3 was considered negative 11/18 (61%).
CONCLUSION: We concluded there is over diagnosis of asthma in obese patients.
CLINICAL IMPLICATIONS: Bronchoprovocation testing should be considered in obese patients with diagnosis of asthma and without spirometric evidence of airway obstruction.
DISCLOSURE: Chirag Mehta, None.