TABLE 3.
Subgroup analyses of the associations of serum calcium quartiles with all-cause mortality.
| Subgroup | HR (95% CI) for all-cause mortality in serum calcium quartiles | |||||
| No. of participants | Q1 [≤2.299] | Q2 [2.300, 2.349] | Q3 [2.350, 2.425] | Q4 [≥2.425] | P for interaction | |
| Gender | 0.859 | |||||
| Female | 25,621 | 1 (ref) | 0.77 (0.62, 0.97) | 0.85 (0.68, 1.05) | 0.87 (0.71, 1.06) | |
| Male | 25,421 | 1 (ref) | 0.82 (0.69, 0.99) | 0.83 (0.69, 0.99) | 0.87 (0.73, 1.03) | |
| Age | 0.353 | |||||
| ≤60 | 35,488 | 1 (ref) | 0.89 (0.68, 1.15) | 0.84 (0.64, 1.10) | 0.87 (0.65, 1.15) | |
| >60 | 15,554 | 1 (ref) | 0.75 (0.64, 0.89) | 0.82 (0.71, 0.94) | 0.80 (0.69, 0.94) | |
| Race | 0.753 | |||||
| White | 22,192 | 1 (ref) | 0.83 (0.70, 0.97) | 0.85 (0.72, 1.00) | 0.90 (0.76, 1.06) | |
| Non-white | 28,850 | 1 (ref) | 0.73 (0.53, 0.99) | 0.80 (0.62, 1.02) | 0.76 (0.61, 0.95) | |
| Education | 0.247 | |||||
| High school or below | 23,850 | 1 (ref) | 0.92 (0.74, 1.13) | 0.87 (0.71, 1.05) | 0.87 (0.71, 1.06) | |
| College or above | 23,623 | 1 (ref) | 0.73 (0.59, 0.90) | 0.84 (0.69, 1.03) | 0.90 (0.73, 1.11) | |
| Marital status | 0.211 | |||||
| Married | 24,912 | 1 (ref) | 0.88 (0.72, 1.07) | 0.93 (0.77, 1.12) | 0.94 (0.79, 1.12) | |
| other | 24,111 | 1 (ref) | 0.72 (0.58, 0.90) | 0.73 (0.59, 0.89) | 0.78 (0.64, 0.95) | |
| PIR | 0.054 | |||||
| <1.3 | 14,908 | 1 (ref) | 0.96 (0.72, 1.27) | 0.92 (0.71, 1.19) | 0.81 (0.65, 1.02) | |
| ≥1.3 | 31,662 | 1 (ref) | 0.76 (0.64, 0.90) | 0.80 (0.68, 0.96) | 0.89 (0.75, 1.04) | |
| BMI | 0.055 | |||||
| ≤28 | 26,346 | 1 (ref) | 0.71 (0.58, 0.87) | 0.72 (0.60, 0.85) | 0.75 (0.63, 0.89) | |
| >28 | 23,811 | 1 (ref) | 0.91 (0.74, 1.12) | 0.98 (0.80, 1.20) | 1.03 (0.83, 1.27) | |
| Smoker | 0.089 | |||||
| Non-smoker | 26,256 | 1 (ref) | 0.72 (0.58, 0.89) | 0.76 (0.62, 0.94) | 0.72 (0.59, 0.89) | |
| Smoker | 22,009 | 1 (ref) | 0.87 (0.72, 1.05) | 0.91 (0.77, 1.07) | 0.97 (0.82, 1.15) | |
| Current drinker | 0.067 | |||||
| No | 14,134 | 1 (ref) | 0.95 (0.77, 1.18) | 0.93 (0.76, 1.13) | 1.03 (0.85, 1.26) | |
| Yes | 29,628 | 1 (ref) | 0.73 (0.60, 0.87) | 0.79 (0.66, 0.94) | 0.78 (0.65, 0.94) | |
| Caffeine consumption | 0.429 | |||||
| ≤P50 | 21,822 | 1 (ref) | 0.87 (0.68, 1.11) | 0.93 (0.74, 1.16) | 0.89 (0.73, 1.09) | |
| >P50 | 21,657 | 1 (ref) | 0.78 (0.65, 0.92) | 0.80 (0.66, 0.95) | 0.87 (0.73, 1.04) | |
| Dietary calcium intake (mg/day) | 0.036 | |||||
| <800 | 22,341 | 1 (ref) | 0.79 (0.65, 0.95) | 0.94 (0.79, 1.13) | 0.94 (0.79, 1.11) | |
| ≥800 | 21,138 | 1 (ref) | 0.84 (0.68, 1.05) | 0.73 (0.60, 0.90) | 0.81 (0.65, 1.02) | |
| HEI2015 | 0.126 | |||||
| ≤50 | 24,417 | 1 (ref) | 0.87 (0.73, 1.03) | 0.86 (0.71, 1.05) | 0.81 (0.67, 0.98) | |
| >50 | 23,598 | 1 (ref) | 0.75 (0.60, 0.92) | 0.82 (0.69, 0.97) | 0.93 (0.77, 1.12) | |
| Physical activity | 0.936 | |||||
| Inactive | 13,112 | 1 (ref) | 0.82 (0.68, 1.00) | 0.81 (0.67, 0.99) | 0.87 (0.72, 1.07) | |
| Active | 23,678 | 1 (ref) | 0.81 (0.65, 1.01) | 0.85 (0.70, 1.03) | 0.88 (0.73, 1.06) | |
| Hypertension | 0.025 | |||||
| No | 30,064 | 1 (ref) | 0.71 (0.56, 0.91) | 0.77 (0.61, 0.98) | 0.70 (0.55, 0.90) | |
| Yes | 20,978 | 1 (ref) | 0.88 (0.74, 1.05) | 0.89 (0.76, 1.05) | 0.99 (0.83, 1.18) | |
| Diabetes | 0.69 | |||||
| No | 42,516 | 1 (ref) | 0.78 (0.66, 0.92) | 0.81 (0.70, 0.95) | 0.86 (0.73, 1.01) | |
| Yes | 8,522 | 1 (ref) | 0.95 (0.71, 1.29) | 1.02 (0.78, 1.33) | 0.95 (0.72, 1.26) | |
| CHD | 0.456 | |||||
| No | 45,284 | 1 (ref) | 0.82 (0.71, 0.96) | 0.82 (0.70, 0.96) | 0.86 (0.74, 1.01) | |
| Yes | 2,043 | 1 (ref) | 0.67 (0.46, 0.99) | 0.94 (0.66, 1.32) | 0.88 (0.60, 1.29) | |
| Stroke | 0.29 | |||||
| No | 45,645 | 1 (ref) | 0.81 (0.70, 0.93) | 0.85 (0.74, 0.99) | 0.87 (0.75, 1.01) | |
| Yes | 1,837 | 1 (ref) | 0.95 (0.58, 1.55) | 0.84 (0.51, 1.38) | 1.12 (0.67, 1.86) | |
| COPD | 0.521 | |||||
| No | 45,561 | 1 (ref) | 0.80 (0.69, 0.93) | 0.84 (0.72, 0.97) | 0.85 (0.73, 0.99) | |
| Yes | 2,011 | 1 (ref) | 0.84 (0.54, 1.30) | 0.81 (0.50, 1.32) | 0.98 (0.62, 1.54) | |
| Cancer | 0.686 | |||||
| No | 43,089 | 1 (ref) | 0.80 (0.68, 0.95) | 0.82 (0.71, 0.96) | 0.85 (0.72, 1.01) | |
| Yes | 4,404 | 1 (ref) | 0.86 (0.65, 1.15) | 0.94 (0.71, 1.25) | 0.98 (0.75, 1.29) | |
| CKD | 0.266 | |||||
| No | 41,277 | 1 (ref) | 0.77 (0.64, 0.92) | 0.84 (0.71, 1.00) | 0.82 (0.69, 0.98) | |
| Yes | 9,217 | 1 (ref) | 0.88 (0.70, 1.11) | 0.84 (0.69, 1.03) | 0.96 (0.77, 1.20) | |
CI, confidence interval; BMI, body mass index; PIR, family income-to-poverty ratio; P50, 50th percentile; HEI, healthy eating index; COPD, chronic obstructive pulmonary disease; CHD, coronary heart disease; CKD, chronic kidney disease.