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Table 1 Main characteristics of included studies

From: Low vitamin D levels are associated with high viral loads in patients with chronic hepatitis B: a systematic review and meta-analysis

First author Year Country Study design Method Season of sampling Latitude Number of CHB patients (male) Age of CHB patients (years)a Number of healthy controls (male) Age of healthy controls (years)a HBV genotype: B/C (n, %) HBV viral loadsa HBeAg status: P/N (n, %) Vitamin D in patients (mean ± SD)(ng/mL) Prevalence of vitamin D deficiency in CHB patients (%) VitaminD in controls (mean ± SD)(ng/mL) Correlation coefficient(r) NOS score
Iacob [24] 2012 Romania Observational ELISA Autumn to spring NA 12(NA) NA 22 (7) 36.22 ± 13.86 NA NA NA 11.5 ± 6.36 NA 12.04 ± 3.99 NA 7
Mohamadkhani [25] 2015 Iran Observational ELISA NA NA 173 (118) 37 ± 9.7 NA NA NA 3.94 ± 1.08c NA 22.19 ± 8.28 42 NA −0.32 6
Chen [26] 2015 China Observational ECL All year round NA 128 (92) 33.57 ± 8.47 128 (95) 35.17 ± 8.02 83 (64.8)/45 (35.2) 6.38 ± 2.32d 91 (71.1)/37 (28.9) 16.88 ± 6.4 75 20.16 ± 5.5 −0.392 8
Hoan [27] 2016 Vietnam Observational ELISA NA NA 165 (135) 39 (18–79)b 122 (82) 40 (19–58)b NA 5.6 (2.4–10.1)b,c NA 21.2 ± 8.9 32.5 23.6 ± 9.5 −0.57f 7
Gao [28] 2016 China Observational ELISA Winter and summer NA 142 (0) 25.8 ± 3.5 251 (0) 26.5 ± 3.8 NA NA 110 (77.5)/32 (22.5) 12.05 ± 3.3 98.6 13.63 ± 5.5 NG 7
Zhao [29] 2016 China Observational HPLC-TMS Winter 38°3′N-39°54′N 115 (89) 51.29 ± 9.26 115 (89) 51.41 ± 9.17 NA 4.10 ± 1.80e 38 (33.0)/77 (67.0) 7.83 ± 3.47 NA 9.76 ± 4.36 NG 8
Sajith [30] 2017 India Observational CL NA NA 79 (79) 40.5 ± 10 58 (58) 38 ± 6.2 NA NA NA 23.2 ± 12.6 31 26.8 ± 8.7 NG 9
  1. Abbreviations: CL chemiluminescence, ECL electrochemiluminescence, ELISA Enzyme-Linked Immunosorbent Assay, HPLC-TMS High Performance Liquid Chromatography Tandem Mass Spectrometry method, NA not applicable, P/N positive/negative, SD standard deviation
  2. a: mean ± SD, unless noted otherwise
  3. b: median (range)
  4. Units of HBV viral loads: c, log copies/mL; d: log IU/mL; e: log IU/L
  5. f: only 63 patients were selected for analysis of the correlation between vitamin D levels and HBV viral loads