| | Authors, year | Covariates |
| | Kim et al. 2013 [18] | Men and premenopausal women adjusted for age, BMI, WBC count, alkaline phosphatase, smoking, alcohol intake, PHA, self-reported health status, daily calcium intake, chronic disease, rheumatoid arthritis, cancer, and parental osteoporosis; postmenopausal women further adjusted for years since menopause and postmenopausal hormone therapy |
| | Maghraoui et al. 2014 [19] | Age, BMI, years since menopause, and number of pregnancies |
| | Lee et al. 2015 [20] | Age, calcium intake, serum 25-OH vitamin D level, serum parathyroid hormone level, smoking status, alcohol consumption, PHA, hormone replacement therapy (in women), and muscle mass |
| | Eckstein et al. 2016 [21] | None |
| | Abbasi et al. 2017 [22] | None |
| | Heidari et al. 2017 [23] | Age, BMI, muscle strength, PHA, educational level, history of fractures, abdominal obesity, smoking, and other biochemical parameters |
| | Chen et al. 2018 [15] | Age, serum total cholesterol, alkaline phosphatase, and nonalcoholic fatty liver disease |
| | Loke et al. 2018 [13] | None |
| | Lin et al. 2018 [14] | Age, aspartate aminotransferase, creatinine, hemoglobin, and exercise status |
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