Abstract
BackgroundSmoking is common in people infected with HIV but cessation support is not a routine part of clinical care. The aim was to assess whether smoking is a risk factor for pneumonia in people with HIV and whether smoking cessation ameliorates excess risk.MethodsWe performed MEDLINE and Embase database searches and included cohort or case-control studies conducted in adult patients infected with HIV extracting a hazard ratio (HR) or odds ratio (OR) that compared the incidence of bacterial pneumonia or pneumonia caused by Pneumocystis jiroveci (PCP) between two smoking categories. Studies were appraised for quality and combined using inverse variance meta-analysis.ResultsFourteen cohort and case-control studies were included. Assessment of outcome was good, but assessment of exposure status was poor. Current smokers were at higher risk of bacterial pneumonia than former smokers: HR 1.37 (95% confidence interval (CI): 1.06, 1.78). There was no evidence that former smokers were at higher risk than never smokers: HR 1.24 (95%CI: 0.96, 1.60). Current smokers were at higher risk of bacterial pneumonia than current non-smokers: HR of 1.73 (95%CI: 1.44, 2.06). There was no evidence that smoking increased the incidence of PCP. The HR for current versus non-smokers was 0.94 (95%CI: 0.79, 1.12), but from case-control studies the OR was 1.76 (95%CI: 1.25, 2.48) with heterogeneity. Confined to higher quality studies, the OR was 0.97 (95%CI: 0.81, 1.16). Residual confounding is possible, but available data suggest this is not an adequate explanation.ConclusionsSmoking is a risk factor for bacterial pneumonia but not PCP and smoking cessation reduces this risk.See related article: http://www.biomedcentral.com/1741-7015/11/16
Highlights
Smoking is common in people infected with human immunodeficiency virus (HIV) but cessation support is not a routine part of clinical care
We conducted a systematic review and meta-analysis of cohort and casecontrol studies to assess whether smoking cessation reduces the incidence of both bacterial pneumonia and Pneumocystis jiroveci pneumonia (PCP) in patients with HIV infection, and looked for evidence of a dose-response relationship to support causality
The studies had to have sufficient information to extract a hazard ratio (HR) or odds ratio (OR) with 95% confidence intervals (CI) that compared the risk of bacterial pneumonia or PCP incidence between two smoking exposure categories
Summary
Smoking is common in people infected with HIV but cessation support is not a routine part of clinical care. Smoking is a risk factor for bacterial pneumonia in the absence of HIV and without evidence of chronic obstructive pulmonary disease It is unclear whether the elevated risk due to smoking is ameliorated by smoking cessation [4,5]. The best evidence of causality that smoking cessation ameliorates risk would come from randomized trials of smoking cessation support versus usual care where the outcomes included incidence of pneumonia. We conducted a systematic review and meta-analysis of cohort and casecontrol studies to assess whether smoking cessation reduces the incidence of both bacterial pneumonia and Pneumocystis jiroveci pneumonia (PCP) in patients with HIV infection, and looked for evidence of a dose-response relationship to support causality. We examined whether there was evidence that any risk from smoking or benefit from cessation was modified by the use of HAART or by CD4 count
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