Table 2.
Odds ratios (95% confidence interval) for hearing impairment in 2014 in relation to mean values of IGF-1 measured in 2008 and 2012: the English Longitudinal Study of Ageing (n = 4390).
| Model | Sex-specific IGF-1 (nmol/L) quintilesa | OR continuousb | P-value linearc | P-value curvatured | ||||
|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | ||||
| Total sample n = 4390, 1680 cases | ||||||||
| Model 0e | 1 (ref) | 0.90 (0.73; 1.11) | 0.95 (0.77; 1.18) | 0.87 (0.70; 1.07) | 1.04 (0.84; 1.28) | 1.00 (0.93; 1.07) | 0.97 | 0.05 |
| Model 1f | 1 (ref) | 1.00 (0.80; 1.24) | 1.05 (0.85; 1.32) | 0.99 (0.80; 1.23) | 1.14 (0.91; 1.41) | 1.02 (0.95; 1.09) | 0.53 | 0.45 |
| Model 2g | 1 (ref) | 0.94 (0.75; 1.18) | 1.04 (0.83; 1.31) | 0.95 (0.76; 1.19) | 1.11 (0.88; 1.40) | 1.01 (0.94; 1.09) | 0.79 | 0.29 |
| Age < 60 years, n = 1400, 261 cases h | ||||||||
| Model 0e | 1 (ref) | 0.72 (0.48; 1.09) | 0.89 (0.60; 1.34) | 0.62 (0.40; 0.94) | 0.61 (0.40; 0.94) | 0.82 (0.71; 0.95) | 0.007 | 0.96 |
| Model 1f | 1 (ref) | 0.83 (0.54; 1.27) | 1.05 (0.69; 1.60) | 0.75 (0.48; 1.16) | 0.72 (0.46; 1.14) | 0.87 (0.75; 1.00) | 0.05 | 0.40 |
| Model 2g | 1 (ref) | 0.80 (0.52; 1.24) | 1.03 (0.66; 1.59) | 0.69 (0.44; 1.10) | 0.71 (0.44; 1.13) | 0.86 (0.73; 1.00) | 0.03 | 0.67 |
| Age ≥60 years, n = 2990, 1419 cases h | ||||||||
| Model 0e | 1 (ref) | 0.91 (0.72; 1.16) | 1.02 (0.79; 1.31) | 0.89 (0.69; 1.14) | 1.20 (0.94; 1.54) | 1.06 (0.98; 1.15) | 0.14 | 0.02 |
| Model 1f | 1 (ref) | 0.98 (0.76; 1.25) | 1.11 (0.86; 1.44) | 0.98 (0.76; 1.27) | 1.28 (0.99; 1.65) | 1.07 (0.99; 1.16) | 0.07 | 0.18 |
| Model 2g | 1 (ref) | 0.93 (0.72; 1.21) | 1.10 (0.84; 1.45) | 0.96 (0.73; 1.26) | 1.24 (0.95; 1.62) | 1.06 (0.98; 1.16) | 0.16 | 0.15 |
aIGF-1 (nmol/L) range in each quintile in the total sample: 3–12.5; 13–15; 15.5–17.5; 18–21; 21.5–52 (men) and 4–11; 11.5–13.5; 14–15.5; 16–19; 19.5–43 (women). Range in the younger group: 3–13.5; 14–16; 16.5–18; 18.5–21; 21.5–34.5 (men) and 4.5–12; 12.5–14.5; 15–17; 17.5–20; 20.5–43 (women). Range in the older group: 4–12; 12.5–15; 15.5–17.5; 18–20.5; 21–52 (men) and 4–10.5; 11–13; 13.5–15; 15.5–18; 18.5–38 (women). bOdds ratio (95% confidence interval) for the increase of 5 nmol/L of IGF-1 concentration when IGF-1 is included as a continuous variable in the model. cp-value of the effect of IGF-1 included as continuous in the regression model. dp-value derived comparing a nested model with a linear or linear and cubic spline terms. If the p-value is low (<0.05), this denotes evidence of a non-linear relation. eModel 0: Adjusted for age (continuous) and sex. fModel 1: Model 0 + height (continuous), smoking status (never, ex-smoker, current), body mass index (BMI, continuous kg/m2), cognitive function (continuous score) at baseline and change, educational level (low, medium, high), physical activity (categorical, 5 levels), self-rated poor health (binary) at baseline and change. gModel 2: Model 1 + self-rated hearing acuity at baseline. hP-value for interaction term between IGF-1 and age was 0.03 (Model 0), 0.05 (Model 1) and 0.10 (Model 2).