Cindy Boer

Vitamin K Antagonist Anticoagulants and Osteoarthritis | 149 3.2 Detailed description of Potential confounders and risk factors Potential confounders and risk factors included age, sex, body Mass Index(BMI) smok- ing status, physical activity, total cholesterol/high-density lipoprotein (HDL) ratio, edu- cation level, baseline OA severity, lower-limb disability, femoral neck Bone Mass Densi- ty (BMD), cohort(RS-I/RS-II), and comorbidities (hypertension and diabetes mellitus) as potential confounders/risk factors. Age (at baseline visit in years), sex, BMI(kg-1m2), smoking status (never, for- mer and current smoker), physical activity(metabolic equivalent of task hours/week), education level (0-3) and lower-limb disability(yes/no) were assessed through home interviews taken by trained interviewers1. Education levels were assessed according to UNESCO classification to define education level (0=primary education, 1 = lower/ intermediate general education or lower vocational education, 2= intermediate voca- tional education or higher general education, 3= higher vocational education or univer- sity).Lower-limb disability was determined for each participant based on the Stanford Health Assessment Questionnaire3. Locomotor disability of the lower-limb was defined as the mean of the scores (with zero indicating no impairment and three indicating un- able to perform) on the six questions related to lower limb functions[3]. Disability was defined as a lower limb disability index of 0.5 or over. Baseline OA severity was determined scoring of radiographs taken at baseline visit. Radiographs were scored by trained medical professional according to the Kell- gren-Lawrence osteoarthrtis severity grading scale4. Femoral neck BMD was measured by DXA-scans as described previously5. Arterial hypertension was defined as a systolic blood pressure of 160 mm Hg or higher, diastolic blood pressure of 95 mm Hg or higher, or the use of antihypertensive drugs for hypertension. Diabetes mellitus was defined as use of glucose-lowering medication or non-fasting random or postload glucose lev- els exceeding 11.0 mmol/liter. Total cholesterol/HDL ration was determined via serum total cholesterol determined by an enzymatic procedure, HDL measured after precipi- tation of non-HDL cholesterol.