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High prevalence of emphysema in middle-aged HIV-positive smokers
Michael Carter, 2018-01-08 10:40

HIV infection is associated with airway obstruction, French investigators report in AIDS. Middle-aged HIV-positive smokers were matched with HIV-negative smokers of the same sex and age. After controlling for potential confounders, the investigators found a significant association between HIV and airway obstruction, an association that persisted after controlling for history of previous serious lung disease. Smoking intensity was also a significant risk factor.

Lung function was measured using forced vital expiratory volume (FEV1) and forced vital capacity (FVC). FEV1 to FVC ratio was the primary outcome, and FEV1/FVC ration below 0.70 and FEV1 below 80% was indicative of moderate to severe chronic obstructive pulmonary disease (COPD).

“We found that HIV infection was independently associated with lower FEV1/FVC ratios,” comment the authors. “HIV was also associated with an increased prevalence of airway obstruction.”

Small airway disease with emphysema results in airway obstruction and possibly chronic obstructive pulmonary disease (COPD). There is an elevated prevalence of this condition in patients with HIV, possibly related to high rates of smoking and previous HIV-related lung disease.

French investigators wished to establish a clear understanding of the risk of airway obstruction in HIV-positive patients, especially those with multiple risk factors for the condition (older age, smoking and previous immune suppression).

They designed a case-controlled study involving 351 HIV-positive patients and 702 age- and sex-matched controls.

Key inclusion criteria were age 40 years or above, smoking history of 20 pack-years or more, nadir CD4 cell count below 350 cells/mm3, and current CD4 cell count above 100 cells/mm3. Recruitment was restricted to current smokers or patients who quit smoking within the previous three years. Patients were excluded if they had had a lung infection within the previous two months.

The median age was 50 years and 17% of participants were women. Participants had smoked for a median of 30 pack-years and 91% of people living with HIV were current smokers comparted with 67% of the HIV-negative control group (p<0.0001). The majority of HIV-positive patients (89%) had an undetectable viral load and the median current CD4 cell count was 573 cells/mm3.

The FEV1/FVC ratio was significantly impaired in patients with HIV compared to the controls (0.74 vs. 0.78, p < 0.0001). Airway obstruction was diagnosed in almost a fifth (19%) of HIV-positive patients compared to 9% of controls (p < 0.0001).

HIV was strongly associated with lower FEV1/FEC values (p = 0.001), as was increasing age (p < 0.0001), increased smoking intensity (p = 0.007) and HCV co-infection (p = 0.008). In contrast, female sex (p = 0.028) and increased BMI (p < 0.0001) were both associated with higher FEV1/FEC values.

The association between HIV and lower FEV1/FVC persisted after exclusion of patients with a history of tuberculosis or pneumocystis (p = 0.006).

“PLWHIV are at increased risk of bacterial infection, pneumocystosis, tuberculosis, conditions which have all been associated with airway obstruction or emphysema,” write the researchers. “However, other mechanisms may also be implicated, as suggested by the persisting association between HIV and FEV1/FVC ratio after excluding study participants with a history of tuberculosis or pneumocystis infection.”

Restricting analysis to patients with a nadir CD4 cell count between 200-350 cells/mm3 found an association between HIV and impaired FEV1/FEC values of borderline significance.

After taking into account potential confounders, there was also a strong association between HIV and airway obstruction (OR = 1.72; 95% CI, 1.08-2.73). Other risk factors were increasing age (OR = 1.77 per 10 years; 95% CI, 1.28-2.43) and intensity of tobacco use (OR = 1.11 per 5 pack-years increase; 95% CI, 1.03-1.20).

“Our study found a higher prevalence of measured airway obstruction in PLWHIV with a history of important immunodeficiency than in age and sex-matched control group smokers 40 years of age or more,” conclude the investigators.