Cindy Boer

Vitamin K Antagonist Anticoagulants and Osteoarthritis | 139 3.2 Table 1: Study population characteristics Study population (RSI & RSII) Non-users (N = 3,750) Acenocoumarol users (N = 268) General characteristics Mean (SD) or N (%) RSI 2,748 (73.3%) 230 (85.8%) RSII 1,002 (26.7%) 38 (14.2%) Age, years 64.2 (6.4) 66.6 (6.8) Females (%) 2,068 (55.1%) 130 (48.5%) Body Mass Index (BMI), kg/m2 26.3 (3.5) 26.9 (3.5) Follow-up period, months, medi- an, [IQR] 76.1 [55.2, 78.5] 76.7 [75.1, 79.4] Osteoarthritis(OA) prevalence at baseline visit† Hip OA (%) 65 (1.7%) 10 (3.7%) Knee OA (%) 264 (7.4%) 26 (9.7%) MGP allele occurrence (rs1800801) Non-risk allele (A/A) 1,345 (38.6%) 90 (37.2%) Risk allele carrier (T/*) 2,137 (61.4%) 152 (62.8%) VKORC1 group occurrence§ Low - AA 522 (15.0%) 45 (18.7%) Intermediate - AB 1,303 (37.5%) 94 (39.0%) High - BB 1,646 (47.4%) 102 (42.3%) * P-values calculated either by the Students T-test for normal distributed data, for non-normal distri- butions the Kruskal-Wallis test and, categorical variables were tested with Chi-squared test. †Osteoarthritis at baseline was defined as radiographic OA, Kellgren-Lawrence score ≥2 in either the left or right or both investigated joints. §VKORC1 groups based on VKORC1 H-Haplotypes and their association with VKORC1 expression/VKAs maintenance dosage; low: low VKORC1 expression and associated with lower required dosage, High: high VKORC1 expression and associated with higher required dosage. coumarol use. These differences may represent true biological differences between the joints. However, this is more likely the effect of low statistical power (tertiles analy- sis) or the statistical power difference between the joints. As there were more cases of knee OA incidence and progression (n=385 joints) in our study cohorts than for hip OA (n=216 joints). MGP, VKORC1 genetics and acenocoumarol affect OA progression Maintenance dosages of VKAs are dependent on genetic variants (single nucleotide variations, SNVs) affecting VKORC1 expression activity[19, 24]. This altered VKORC1 ex- pression can also affect MGP γ-carboxylation, as VKORC1 is needed for γ-carboxylation by vitamin K, process that is needed to activate MGP . We therefore examined the extent to which acenocoumarol users with a genetic predisposition for decreased MGP and/or