Reply: Chronic obstructive pulmonary disease in rheumatoid arthritis
— Letter to the Editor —
Te-Chun Shen 1, 2, 3; Cheng-Li Lin 4; Chia-Hung Chen 1, 3; Chih-Yen Tu 1; Te-Chun Hsia 1; Chuen-Ming Shih 1; Wu-Hui Hsu 1; Fung-Chang Sung 3
1 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung 404, Taiwan
2 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chu
Shang Show Chwan Hospital, Nantou 557, Taiwan
3 Institute of Clinical Medical Science, College of Medicine, China Medical University,
Taichung 404, Taiwan
4 Management Office for Health Data, China Medical University Hospital, Taichung 404,
Taiwan
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Corresponding author:
Fung Chang Sung, PhD, MPH.
Professor
Institute of Clinical Medical Science, China Medical University,
91 Hsueh-Shih Road, Taichung 404, Taiwan
E-mail address: [email protected] Telephone: +886-4-2205-2121 ext 7520 Fax: 886-4-2203-9216
Conflict of interest: None declared.
Contributorship:
Conception and interpretation: all authors;
Drafting the manuscript: TC Shen, FC Sung.
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Text
From the authors:
We are grateful to Dr. Aggarwal for his interest in our article (1). In the present study, we considered the combined effects of rheumatoid arthritis (RA) and smoking lead to increase the incidence of chronic obstructive pulmonary disease (COPD). Although the smoking rate was estimated to be only about 4% among Taiwanese females, they represent almost 80% of the case group. We have listed this point in the study limitation. We totally agree that a future study with four subgroups (RA smokers, RA non-smokers, non-RA smokers, non-RA non-smokers) will be ideal.
Although respiratory failure is one of the causes of death in RA patients on autopsy, we would not consider it for the clinical evaluation of prognosis. On clinical performance, respiratory failure can be acute, chronic and even both. In addition, respiratory failure is a syndrome with several kinds of mechanism such as low fraction of inspired oxygen (FiO2), hypoventilation, ventilation/perfusion ratio (V/Q) mismatch, shunt, and diffusion impairment. Respiratory failure is not affected only by COPD or RA. Another concern is that respiratory failure may be an inaccurate and inadequate diagnosis on death certificates (2). Hence, instead evaluating respiratory failure, we suggest evaluating the incidence of pneumonia or COPD acute exacerbation for evaluating prognosis.
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Reference
1. Shen TC, Lin CL, Chen CH, Tu CY, Hsia TC, Shih CM, et al. Increased risk of chronic
obstructive pulmonary disease in patients with rheumatoid arthritis: a population-based
cohort study. QJM 2014; 107: 537-43.
2. Ravakhah K. Death certificates are not reliable: revivification of the autopsy. South Med J
2006; 99: 728-33.
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