Association between the frequency of admission for pneumonia and the incidence of in-hospital cardiac arrest: A population-based case-control study

Objective: To examine the association between the frequency of admission for pneumonia and the incidence of in-hospital cardiac arrest. Methods: We enrolled 1739 patients with in-hospital cardiac arrest and 6956 randomly selected age- and sex-matched control patients using a longitudinal claims sub-dataset from 1996 to 2011 for 1 million people randomly selected from the population covered by the Taiwan National Health Insurance program. The odds ratio of in-hospital cardiac arrest associated with the number of hospital admissions for pneumonia was calculated. Results: During the 15-year study period, the in-hospital cardiac arrest group had a higher frequency (28.4% vs 8.1%, p < 0.0001) of admission for pneumonia compared to the control group. The comorbidities of heart failure, chronic pulmonary disease, diabetes, renal failure, liver disease, lymphoma, alcohol abuse, and drug abuse were higher in the in-hospital cardiac arrest group than in the control group. In addition, the risk of in-hospital cardiac arrest was 3.37 for the patients admitted for pneumonia, and the risk of in-hospital cardiac arrest increased for patients with multiple admissions for pneumonia (once, 3.03; two times, 3.44; and three times, 4.42). In cross-analysis, the more admissions for pneumonia and the greater the number of comorbidities, the higher the risk of in-hospital cardiac arrest (odds ratio = 21.37, 95% confidence interval = 13.6-33.9 for patients with more than three admissions for pneumonia and more than three comorbidities). Conclusion: Higher admission frequency for pneumonia was associated with a higher risk of in-hospital cardiac arrest. Awareness of this risk factor may help clinicians provide early prevention or detection for patients with potential in-hospital cardiac arrest risks immediately after admission.