Kenji Ito1, Toshiki Maeda2, Kazuhiro Tada3,2, Koji Takahashi3, Tetsuhiko Yasuno3, Kosuke Masutani3, Shigeaki Mukoubara4, Hisatomi Arima2, Hitoshi Nakashima3. 1. Division of Nephrology and Rheumatology, Department of Internal Medicine, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan. kito@fukuoka-u.ac.jp. 2. Department of Preventive Medicine and Public Health, Faculty of Medicine, Fukuoka University, Fukuoka, Japan. 3. Division of Nephrology and Rheumatology, Department of Internal Medicine, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan. 4. Nagasaki Prefecture Iki Hospital, Iki, Japan.
Abstract
BACKGROUND: Studies regarding harmful effects of smoking on the new-onset of chronic kidney disease (CKD) have been limited. Thus, we collected and retrospectively studied 8 years of data from the annual health check-ups of the residents in Iki City (Nagasaki Prefecture, Japan). METHODS: From 2008 to 2016, 4540 adults were enrolled in the study. Information on smoking habits was obtained via a self-reported questionnaire. New-onset CKD was defined as a reduction of the estimated globular filtration rate (eGFR) to less than 60 mL/min/1.73 m2 and/or new-onset proteinuria during the follow-up examinations. RESULTS: During an average follow-up of 4.6 years, proteinuria developed in 218 people (10.4 per 1000 person-years) and eGFR decline to less than 60 mL/min/1.73 m2 was confirmed in 594 people (28.3 per 1000 person-years) including 53 who showed both proteinuria and eGFR reduction (2.8 per 1000 person-years). In terms of proteinuria, current smokers showed a higher incidence than non-smokers (14.1 and 9.17 per 1000 person-years, respectively, p = 0.001), and a significantly high hazard ratio (HR) of 1.39 with a 95% CI of 1.01-1.92 in multivariable Cox's proportional-hazard analyses. The tendency was more drastic among younger participants (p = 0.015 for trend): current smokers who were < 50 years old had a significantly higher HR of 2.55 with a 95% CI of 1.01-6.45 (p = 0.004) than non-smokers. CONCLUSIONS: Smoking significantly increased the risk for new-onset of CKD based on proteinuria development in a Japanese population without CKD, and the association was more predominant in the younger population.
BACKGROUND: Studies regarding harmful effects of smoking on the new-onset of chronic kidney disease (CKD) have been limited. Thus, we collected and retrospectively studied 8 years of data from the annual health check-ups of the residents in Iki City (Nagasaki Prefecture, Japan). METHODS: From 2008 to 2016, 4540 adults were enrolled in the study. Information on smoking habits was obtained via a self-reported questionnaire. New-onset CKD was defined as a reduction of the estimated globular filtration rate (eGFR) to less than 60 mL/min/1.73 m2 and/or new-onset proteinuria during the follow-up examinations. RESULTS: During an average follow-up of 4.6 years, proteinuria developed in 218 people (10.4 per 1000 person-years) and eGFR decline to less than 60 mL/min/1.73 m2 was confirmed in 594 people (28.3 per 1000 person-years) including 53 who showed both proteinuria and eGFR reduction (2.8 per 1000 person-years). In terms of proteinuria, current smokers showed a higher incidence than non-smokers (14.1 and 9.17 per 1000 person-years, respectively, p = 0.001), and a significantly high hazard ratio (HR) of 1.39 with a 95% CI of 1.01-1.92 in multivariable Cox's proportional-hazard analyses. The tendency was more drastic among younger participants (p = 0.015 for trend): current smokers who were < 50 years old had a significantly higher HR of 2.55 with a 95% CI of 1.01-6.45 (p = 0.004) than non-smokers. CONCLUSIONS: Smoking significantly increased the risk for new-onset of CKD based on proteinuria development in a Japanese population without CKD, and the association was more predominant in the younger population.