Association between dipstick proteinuria and hearing impairment in health check-ups among Japanese workers: a cross-sectional study

OBJECTIVE: Prevention of hearing impairment is important because it is difficult to recover from it. Epidemiological studies have examined the risk factors for hearing impairment; however, the association between dipstick proteinuria and hearing impairment has not been previously examined. This study aimed to clarify the association between dipstick proteinuria and hearing impairment. DESIGN: Cross-sectional study. SETTING: Office and factory workers from all over Japan. PARTICIPANTS: The total number of subjects was 7005. All were employees of the same company. Of these, we recruited 6192 subjects who underwent dipstick urine test and hearing test by audiometry in annual health check-ups (mean age 44.9 years, men 88.3%). PRIMARY OUTCOMES: Hearing tests were performed at two frequencies (1 kHz, 4 kHz) as prescribed by law in Japan. We defined the inability of subjects to respond to 30 dB at 1 kHz and/or 40 dB at 4 kHz as overall moderate hearing impairment. In addition, we defined moderate hearing impairment at 1 kHz (4 kHz) as an abnormal finding at 1 kHz (4 kHz). We examined the associations between degree of dipstick proteinuria and hearing impairment after adjustment for age, sex, body mass index, hypertension, diabetes mellitus, serum creatinine level and history of noisy work environment. RESULTS: Overall moderate hearing impairment was noted in 324 subjects (5.2%). Of these, 107 subjects (1.7%) had moderate hearing impairment at 1 kHz and 278 subjects (4.5%) at 4 kHz. Dipstick proteinuria was significantly associated with overall moderate hearing impairment, as well as moderate hearing impairment at both 1 kHz and 4 kHz. The prevalence of overall moderate hearing impairment among subjects with proteinuria ≥2+ was 23.5%, while that among subjects without proteinuria was 5.2% (p<0.01). CONCLUSIONS: Dipstick proteinuria was associated with moderate hearing impairment in Japanese workers.