Characteristics of small airway disease in patients with HIV infection: insights from spirometry and impulse oscillometry.

BACKGROUND

Airway diseases that are independent of smoking behaviour are frequent in people living with HIV (PLWH). Spirometry, the gold standard for diagnosing airway diseases, may not detect small airway disease (SAD) when forced expiratory volume in 1 s/forced vital capacity is normal. However, impulse oscillometry (IOS) can detect SAD even when the spirometry is normal. This study aims to evaluate characteristics of SAD in PLWH by using IOS and exploring the diagnostic performance of IOS measurements to detect SAD.

METHODS

This cross-sectional study included 127 PLWH on antiretroviral therapy without known airway disease. IOS was done first, followed by spirometry. Patients whose maximal mid-expiratory flow (MMEF) value was below 65% were defined as having spirometric SAD. Clinical characteristics and IOS measures were compared between those who had and those who did not have SAD. A receiver operating characteristic analysis was done to determine the diagnostic performance of IOS measures to diagnose spirometric SAD.

RESULTS

Mean age was 43.5±12.5 years and 60 patients were non-smokers. Spirometric SAD was observed in 34% of all patients. R5, R5-R20, AX and Fres were significantly higher in the patients who had spirometric SAD. Smoking history, duration of antiretroviral therapy and history of pneumonia were significantly associated with SAD. The optimal cut-off value for R5-R20 was 0.08 for SAD (sensitivity of 71.8% and specificity of 58.1%) and the optimal cut-off value for AX was 0.55 (sensitivity of 51.2% specificity of 91.7%).

CONCLUSION

SAD is common in PLWH and IOS may serve as a supportive tool for the clinical assessment of small airway involvement.