Prevalence of undiagnosed chronic obstructive pulmonary disease in patients with suspected sleep apnea syndrome

Objectives:

The purpose was to assess, in a population of patients referred for consultation due to symptoms compatible with obstructive sleep apnea (OSA), whether patients who were smokers or former smokers also had associated COPD (so-called Overlap Syndrome) that had not yet been diagnosed.

Methods:

Descriptive study of 106 patients referred from Primary Care to a specialized Pneumology office with suspected OSA. In addition to the usual protocol for OSA (anthropometric measures, cardiovascular risk factors, symptoms questionnaire and Epworth scale), patients were asked about smoking and symptoms consistent with chronic bronchial disease. Each patient underwent lung function test. Those who were diagnosed with COPD (smokers of > 20 pack years; FEV1/FVC ratio < 0.7 and compatible symptoms) were treated with bronchodilators and instructed in the use.

Results:

We studied 3 groups: non-smokers, smokers and former smokers. The first group consisted of 52 patients (50% men) who were never smokers without COPD (age 53 ± 13; FVC mL 4306 ± 669 mL; FVC 91%, FEV1 mL 3500 ± 716; FEV1 97%; FEV1/FVC 80%). Of the 34 smokers, 12 (35.2%) were confirmed to be suffering from COPD, while among the 20 former smokers, 10 patients (50%) were so diagnosed. In both groups the average degree of severity was very similar: GOLD Stage 2 (moderate). The characteristics of COPD groups are shown in the table. The most frequent symptom of bronchial disease was dyspnea (70% of patients, followed by cough and sputum in 40%).

	COPD (smokers)	COPD (former smokers)
Patients	12	10
Sex	8 men	10 men
Age	52.5 ± 11.1	64.8 ± 11
Average number of cigarettes/day	20.2 ± 10	-
Years as former smoker	-	18.1 ± 12.5
Weight	106.6 ± 16.8	100 ± 17.9
Height	175 ± 7.5	173 ± 10
BMI	34.8	33.4
FVC mL	2636 ± 1379	2698 ± 598
FVC%	60 ± 20	63 ± 18
FEV 1 mL	2003 ± 938	2038 ± 561
FEV1%	62.2 ± 19.3	67 ± 14.2
FEV1/FVC	62	74
Hypertension	6 (50%)	4 (40%)
Diabetes	3 (25%)	1 (10%)

Conclusions:

35% of patients who were active smokers and 50% of former smokers referred for assessment of possible OSA had associated COPD (moderate GOLD stage) that had not yet been diagnosed. This reflects the importance of always conducting an overall respiratory assessment in any patient with possible OSA who is a smoker or former smoker.