What is the association between cystatin C, both as an independent biomarker and as a marker of kidney function, and the 20-year incidence of hearing impairment in middle-aged and older adults?
In this longitudinal, population-based study of 863 participants in the Epidemiology of Hearing Loss Study aged 48 to 86 years at baseline, reduced kidney function as estimated using cystatin C, but not cystatin C alone, was associated with an increased risk of developing hearing impairment during 20 years of follow-up.
Some age-related hearing impairment may occur in conjunction with or as the result of reduced kidney function.
Hearing impairment (HI) is one of the most common conditions affecting older adults. Identification of factors associated with the development of HI may lead to ways to reduce the incidence of this condition.
To investigate the association between cystatin C, both as an independent biomarker and as a marker of kidney function, and the 20-year incidence of HI.
Design, Setting, and Participants
Data were obtained from the Epidemiology of Hearing Loss Study (EHLS), a longitudinal, population-based study in Beaver Dam, Wisconsin. Baseline examinations began in 1993 and continued through 1995, and participants were examined approximately every 5 years, with the most recent examination phase completed in 2015. The EHLS participants with serum cystatin C concentration data and without HI at the baseline examination were included in this study.
Main Outcomes and Measures
Participants without HI were followed up for incident HI (pure-tone average of hearing thresholds at 0.5, 1, 2, and 4 kHz >25 dB hearing level in either ear) for 20 years. Cystatin C was analyzed as a biomarker (concentration) and used to determine estimated glomerular filtration rate (eGFRCysC). Discrete-time Cox proportional hazards regression models were used to analyze the association between cystatin C concentration and eGFRCysC and the 20-year cumulative incidence of HI.
There were 863 participants aged 48 to 86 years with cystatin C data and without HI at baseline. Of these, 599 (69.4%) were women. In models adjusted for age and sex, cystatin C was associated with an increased risk of developing HI (hazard ratio [HR], 1.20; 95% CI, 1.07-1.34 per 0.2-mg/L increase in cystatin C concentration), but the estimate was attenuated after further adjusting for educational level, current smoking, waist circumference, and glycated hemoglobin (HR, 1.11; 95% CI, 0.98-1.27 per 0.2-mg/L increase in cystatin C concentration). Low eGFRCysC was significantly associated with the 20-year cumulative incidence of HI in both the age- and sex-adjusted model (HR, 1.70; 95% CI, 1.16-2.48; <60 vs ≥60 mL/min/1.73 m2) and the multivariable-adjusted model (HR, 1.50; 95% CI, 1.02-2.22; <60 vs ≥60 mL/min/1.73 m2).
Conclusions and Relevance
Reduced kidney function as estimated using cystatin C, but not cystatin C alone, was associated with the 20-year cumulative incidence of HI, suggesting that some age-related HI may occur in conjunction with or as the result of reduced kidney function.
Schubert CR, Paulsen AJ, Nondahl DM, et al. Association Between Cystatin C and 20-Year Cumulative Incidence of Hearing Impairment in the Epidemiology of Hearing Loss Study. JAMA Otolaryngol Head Neck Surg. Published online April 26, 2018. doi:10.1001/jamaoto.2018.0041
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