Chronic pulmonary disease continues to be a major cause of morbidity and mortality in individuals living with the human immunodeficiency virus, even with optimal HIV control. And this is independent, as seen in many studies, of age, smoking, and pulmonary infections.
Both chronic pulmonary obstructive disease (COPD) and lung cancer occur more frequently in people living with HIV than in the general population, and at earlier ages, and with worse outcomes. The risk for emphysema and interstitial lung abnormalities also appears to be higher, research has shown. And asthma has also recently emerged as another important lung disease in people with HIV (PWH).
Dr. Kristina Crothers
“There is evidence that the severity of immunocompromise associated with HIV infection is linked with chronic lung diseases. People who have a lower CD4 cell count or a higher viral load do have an increased risk of COPD and emphysema as well as potentially lung cancer. ,” said Kristina Crothers, MD, professor in the division of pulmonary, critical care, and sleep medicine at the University of Washington, Seattle.
Research has evolved from a focus on the epidemiology of HIV-related chronic lung diseases to a current emphasis on “trying to understand further the mechanisms [behind the heightened risk] through more benchwork and corollary translational studies, and then to the next level of trying to understand what this means for how we should manage people with HIV who have chronic lung diseases,” Dr. Crothers said. “Should management be tailored for people with HIV infection?”
Impairments in immune pathways, local and systemic inflammation, oxidative stress, dysbiosis, and accelerated cellular senescence are among potential mechanisms, but until ongoing mechanistic research yields more answers, pulmonologists should simply – but importantly – be aware of the increased risk and have a low threshold for investigating respiratory symptoms, she and other experts said in interviews. Referral of eligible patients for lung cancer screening is also a priority, as is smoking cessation, they said.
Notably, while spirometry has been the most commonly studied lung function measure in PWH, another noninvasive measure, diffusing capacity for carbon monoxide (DLCO), has garnered attention in the past decade and thus far appears to be the more frequent lung function abnormality.
In an analysis published in 2020 from the longitudinal Multicenter AIDS Cohort Study (MACS) – a study of a subcohort of 591 men with HIV and 476 without HIV – those with HIV were found to have a 1.6-fold increased risk of mild DLCO impairment (< 80% of predicted normal) and a 3-fold higher risk of more severe DLCO impairment (< 60% of predicted normal). There was no significant difference in spirometry findings by HIV status.
Such findings on DLCO are worthy of consideration in clinical practice, even in the absence of HIV-specific screening guidelines for noncommunicable lung diseases, Dr. Crothers said. “In thinking about screening and diagnosing chronic lung diseases in these patients, I’d not only consider spirometry, but also diffusing capacity” when possible, she said. Impaired DLCO is seen with emphysema and pulmonary vascular diseases like pulmonary hypertension and also interstitial lung diseases.