Cigarette smoking, proteinuria, and renal function in middle-aged Japanese men from an occupational population

Abstract

Objectives To clarify the renal effects of cigarette smoking in a middle-aged occupational population because the effects have previously been demonstrated mainly in community populations that included many elderly people who are thought to be vulnerable to such effects. Methods In 990 middle-aged men recruited from a chemical plant, proteinuria was measured by a dipstick method and the glomerular filtration rate was estimated (eGFR) using a formula proposed by the Japanese Society of Nephrology. Results Proteinuria was found in 4.6% of the current smokers and 1.5% of the never-smokers. It was found in 4.8% of the subjects having a Brinkman index (BI) of 400-599 and 6.3% of those having a BI of 600 or above. The odds ratio for proteinuria in them was 2.94 (CI: 1.01-8.55) and 3.61 (CI: 1.29-10.1), respectively, adjusting for possible confounders. The mean eGFR was higher in smokers than in nonsmokers throughout middle age up to 64 years. Normal but high eGFR was found in 6.7% of the current heavy smokers and subnormal eGFR in 5.7% of the largest cumulative cigarette consumers in contrast to 3.0% or less of the never-smokers. Proteinuria was found in 13.3% of the subjects showing subnormal eGFR, specifically in 16.7% of the smokers and 8.3% of the nonsmokers. Conclusions Smoking causes proteinuria in working middle-aged men. Smokers tend to have a high eGFR, but those with subnormal eGFR showed proteinuria most frequently. Whether the high eGFR in smokers will eventually decrease and cause proteinuria remains an important focus for further studies.

The effects of continuing and discontinuing smoking on the development of chronic kidney disease (CKD) in the healthy middle-aged working population in Japan

“…There was a tendency for smokers to have a higher GFR than non-smokers. Our findings of a higher GFR and a lower risk of low GFR in smokers are consistent with those reported previously for general populations, especially in studies on workplaces [8][9][10]12]. Our results confirm that the elevated GFR in smokers was caused by smoking since a large reduction in GFR was observed after individuals stopped smoking.…”

“…Mild alcohol consumption had a significant protective effect on the reduction of GFR in our study cohort, which is consistent with the findings in our previous cross-sectional study [9]. The anti-atherogenic property of mild alcohol consumption [33][34][35] may have even had a protective role on renal function.…”

“…Data on cigarette and alcohol consumption were obtained by interview by experienced nurses, as described in our previous studies [9,11]. Smoking habits were classified into four categories, namely, lifelong non-smokers, exsmokers, current smokers consuming up to one pack per day, and smokers consuming more than one pack per day.…”

“…In addition to the limitations related to the sensitivity of dipstick-measured proteinuria, the validity of eGFR using the JSN equation [9], and the single measurements of those parameters, the selection of the study subjects should also be considered a limitation in our study. Japanese companies are mandated to have their workers aged 35-40 years or older take annual health check-ups, including blood tests of liver enzyme activities and serum lipid concentrations.…”

“…Furthermore, many of the previous studies carried out in workplaces were cross-sectional in design [8][9][10][11][12]. The few longitudinal studies conducted in workplaces that have been conducted to date are limited to a small number of subjects [13] or to a short observational period [14].…”