Table 1 Characteristics of studies included in the meta-analysis of 25-hydroxyvitamin D concentration and risk of rheumatoid arthritis
From: Vitamin D status and risk of rheumatoid arthritis: systematic review and meta-analysis
Author, year of publication | Study name or description; location | Study period; follow-up duration | Number of participants and cases; sex; age | Study design; outcome assessment | Method of 25(OH)D measurement | 25(OH)D comparison | RR, OR, or HR and 95% CI | Adjustments for covariates | NOS score |
|---|---|---|---|---|---|---|---|---|---|
Brink et al. 2018 [34] | Northern Sweden Health and Disease Study (NSHDS), comprising the Västerbotten intervention program [VIP], monitoring trends and determinants in cardiovascular disease [MONICA] and the Mammography screening project Sweden | mean 6.2 years to diagnosis | 515 cases, 267 controls Women: 365 cases, 188 controls Men: 150 cases, 79 controls Mean age: 52.2 years for cases, 53.3 years for controls | Nested case–control study Case criteria: patients fulfilling the 1987 American Rheumatism Association classification criteria for RA, with blood sampled before date of symptom onset Controls randomly selected from the same cohorts, matched 2:1 for age, sex, date of blood sample | Liquid chromatography-tandem mass spectrometry | Per 1 nmol/La | OR Women 0.99 (0.99–1.00) Men 1.00 (0.99–1.02) | Age, season, BMI, ever smoking, educational level | 8 |
Mean 25(OH)D Cases: 53.8Â nmol/L Controls: 54.5Â nmol/L | Â | ||||||||
Cote et al. 2014 [33] | Electronic health records in the Geisinger Health System (GHS) USA | 2001–2012 median 125.5 days (range 1–2247 days) between 25(OH)D measurement and incident RA | 270 cases, 1341 controls Women: 225 cases, 1125 controls Men: 45 cases, 216 controls Median age: 62.4 years at diagnosis | Case–control study with retrospective 25(OH)D measurements Case criteria: incident RA defined as ICD-9 code 714.0 twice by a rheumatologist, with at least one 25(OH)D level recorded prior to diagnosis Controls selected from the general GHS population, matched 5:1 for age and gender | DiaSorin radioimmunoassay (2001–September 2006); liquid chromatography-tandem mass spectrometry (October 2006–May 2009); DiaSorin LIAISON (June 2009–November 2012) median 25(OH)D 31 ng/ml (IQR 23–39) | Continuous, per 1 ng/mlb | OR 0.996 (0.987–1.005) Women 0.995 (0.985–1.006) Men 0.997 (0.977–1.018) | Age and sex as matching factors and adjusted for BMI and smoking status (ever/never) | 6 |
 < 30 vs ≥ 30 ng/ml | 0.982 (0.748–1.291) Women 0.929 (0.685–1.259) Men 1.226 (0.647–2.324) | ||||||||
 < 20 vs ≥ 20 ng/ml | 1.124 (0.803–1.573) Women 1.198 (0.829–1.730) Men 0.855 (0.361–2.025) | ||||||||
Hiraki et al. 2014 [31] | Nurses’ Health Study (NHS) USA | Recruited 1976, blood sampling 1989–1990, follow-up until June 2006 Mean 7.8 years between blood draw and RA diagnosis | 120 cases, 357 controls Women only Mean age 56.0 years at blood draw; 63.8 years at RA diagnosis | Nested case–control study Case criteria: self-reported on biennial follow-up survey, followed by CTD Screening Questionnaire. Confirmed against standardized ACR classification criteria for RA through review of medical records by two board-certified rheumatologists Controls selected from participants with stored blood, matched 3:1 on age (± 1 year), menopausal status and postmenopausal hormone use, month and year of blood collection, time of day and fasting status at blood draw | Radioimmunoassay Mean 25(OH)D not reported | Continuous, per 1 ng/ml increase | ORc 1.01 (0.99–1.04) | Smoking status (ever/never), parity and breastfeeding, alcohol consumption, BMI, median income, region of USA residence; conditioned on matching factors (age, date of blood draw, fasting status, menopausal status, hormone use) | 7 |
 > 20 vs ≤ 20 ng/ml | 1.30 (0.78–2.16) | ||||||||
Highest vs lowest quartile | 1.51 (0.75–3.05) | ||||||||
Per 1 ng/ml increase | Stratified by time between blood draw and diagnosis: 3 months– < 4 years 0.94 (0.85–1.04)  ≥ 4 years 1.02 (0.99–1.05) | ||||||||
Hiraki et al. 2014 [31] | Nurses’ Health Study II (NHSII) USA | Recruited 1989, blood sampling 1996–1999, follow-up until 2007 Mean 4.2 years between blood draw and RA diagnosis | 46 cases, 133 controls Women only Mean age 44.5 years at blood draw; 48.5 at RA diagnosis | Nested case–control study Case criteria: self-reported on biennial follow-up survey, followed by CTD Screening Questionnaire. Confirmed against standardized ACR classification criteria for RA through review of medical records by two board-certified rheumatologists Controls selected from participants with stored blood, matched 3:1 on age (± 1 year), menopausal status and postmenopausal hormone use, month and year of blood collection, time of day and fasting status at blood draw, and additionally matched to premenopausal cases based on menstrual cycle phase | Radioimmunoassay Mean 25(OH)D not reported | Continuous, per 1 ng/ml increase | ORc 0.98 (0.94–1.03) | Smoking status (ever/never), parity and breastfeeding, alcohol consumption, BMI, median income, region of USA residence; conditioned on matching factors (age, date of blood draw, fasting status, menopausal status, hormone use, and menstrual cycle timing) | 7 |
 > 20 vs ≤ 20 ng/ml | 0.97 (0.38–2.50) | ||||||||
Highest vs lowest quartile | 0.66 (0.17–2.56) | ||||||||
Per 1 ng/ml increase | Stratified by time between blood draw and diagnosis: 3 months ≤ 4 years 0.80 (0.64–0.99) ≥ 4 years 1.00 (0.92–1.08) | ||||||||
Skaaby et al 2015 [32] | Monica10 Denmark | Recruited 1993–1994, follow-up until 31 Dec 2010 Median 16.4 years | Total 2649; 43 cases 50.2% men Mean age 55.4 years (range 40–71 years) | Population-based study, random sample of the population recruited from the Danish Central Personal Register Seropositive RA (ICD-8 codes 712.19, 712.39, 712.59 or ICD-10 codes M05-M06) identified by linkage to the Danish National Patient Register which contains information on admissions to Danish hospitals since 1978 | IDS-SYS 25-Hydroxy Vitamin D method Mean 25(OH)D 64.7 nmol/L | Per 10 nmol/L higher 25(OH)D | HRd 1.01 (0.88–1.15) | Age, sex, education, season of blood sample, physical activity, smoking habits, alcohol intake, BMI, systolic and diastolic blood pressure, serum total cholesterol, serum triglycerides | 9 |
Skaaby et al 2015 [32] | Inter99 Denmark | Recruited 1999–2001, follow-up until 31 Dec 2010 Median 11.0 years | Total 6497; 47 cases 49.2% men Mean age 46.1 years (range 30–60 years) | Population-based study, random sample of the population recruited from the Danish Central Personal Register, randomised controlled trial that investigated effects of lifestyle interventions on cardiovascular disease Seropositive RA (ICD-8 codes 712.19, 712.39, 712.59 or ICD-10 codes M05-M06) identified by linkage to the Danish National Patient Register which contains information on admissions to Danish hospitals since 1978 | High-performance liquid chromatography Mean 25(OH)D 51.2 nmol/L | Per 10 nmol/L higher 25(OH)D | HRd 0.94 (0.82–1.08) | Age, sex, education, season of blood sample, physical activity, smoking habits, alcohol intake, BMI, systolic and diastolic blood pressure, serum total cholesterol, serum triglycerides | 9 |
Skaaby et al. 2015 [32] | Health2006 Denmark | Recruited 2006–2008, follow-up until 31 Dec 2010 Median 3.5 years | Total 3409; 8 cases 44.9% men Mean age 49.4 years (range 18–69 years) | Population-based study, random sample of the population recruited from the Danish Central Personal Register Seropositive RA (ICD-8 codes 712.19, 712.39, 712.59 or ICD-10 codes M05-M06) identified by linkage to the Danish National Patient Register which contains information on admissions to Danish hospitals since 1978 | Roche Diagnostics immunoassay using Cobas e411 Mean 25(OH)D 44.3 nmol/L | Per 10 nmol/L higher 25(OH)D | HRd 1.02 (0.63–1.67) | Age, sex, education, season of blood sample, physical activity, smoking habits, alcohol intake, BMI, systolic and diastolic blood pressure, serum total cholesterol, serum triglycerides | 8 |