Diabetes mellitus with poor glycemic control is a risk factor for pneumonia in COPD

Background

Pneumonias are events of great prognostic significance in COPD, so it is important to identify predictive factors.

Objective

To determine whether poor glycemic control is related to an increased risk of pneumonia in COPD.

Method

A historical cohort study conducted in a COPD clinic. The first severe exacerbation after the first visit was analyzed. Exacerbations that presented with pulmonary infiltrates were identified. A Cox proportional hazards analysis was performed including the values of glycosylated hemoglobin (Hb1Ac) in patients with diabetes mellitus (DM) and variables that could plausibly be related to the risk of pneumonia. The best Hb1Ac value to predict pneumonia was assessed using receiver-operating characteristics analysis.

Results

There were 1124 cases included in the study. A total of 411 patients were admitted to the hospital at least once and 87 were diagnosed with pneumonia. Variables associated with the risk of pneumonia were previous admissions due to COPD and Hb1Ac values (HR: 2.33, 95% CI: 1.06 – 5.08, p = 0.03). A higher body mass index (BMI) was associated with a lower risk of pneumonia. The optimal cutoff point for Hb1Ac to predict pneumonia risk was 7.8 %. The patients were classified into 3 groups: (1) no DM, (2) controlled DM (Hb1AC < 7.8 %), (3) uncontrolled DM (Hb1AC ≥ 7.8 %). The risk of pneumonia for group 2 was not different from group 1, while the risk for group 3 was significantly higher than for groups 1 and 2 (HR: 4.52, 95 % CI: 1.57 – 13.02).

Conclusions

Poor control of DM is a predictor of the risk of pneumonia in COPD. The cutoff point of 7.8 % for this variable seems to be the most useful to identify patients at risk.