Abstract| Volume 24, SUPPLEMENT 1, S256, April 2016

Association of oral calcium intake with osteoarthritis progression and knee replacement: Data from the Osteoarthritis Initiative

      Purpose: To determine the association between baseline and follow-up status of nutritional calcium intake and oral calcium supplementation and clinical and radiographic OA progression and knee replacement (KR).
      Methods: Using data from the Osteoarthritis Initiative (OAI) cohort (n = 4796; mean (± standard deviation) age: 61.2 ± 9.2), adjudicated KR was assessed by the 8th year. The amount of nutritional calcium intake and oral supplementation at baseline and follow-up were estimated using “brief block 2000” questionnaire. The analysis was repeated excluding the subjects who had also received vitamin D supplementation. Radiographic OA progression was determined as increase in Kellgren and Lawrence (KL) score, decrease in the Joint Space Width (JSW) and clinical progression was defined as increase in Western Ontario and McMaster (WOMAC) total score the at 3rd year of follow-up using logistic regression with covariate adjustment for the effect of baseline age, gender, BMI, Physical Activity Scale for the Elderly (PASE), WOMAC and KL score.
      Results: At baseline, every 100 mg of oral calcium supplementation but not nutritional intake was associated with KL score increase (Adjusted OR: 1.03 (1.01–1.05); P value: 0.016) and KR (Adjusted Hazard Ratio (HR): 1.07 (1.04–1.10); P value<0.001). In the follow-up visits, each additional year of calcium supplementation after enrollment was associated with increase in KL score (Adjusted OR: 1.10 (1.01–1.21); P value: 0.030), WOMAC score (Adjusted OR: 1.07 (1.01–1.14); P value: 0.022) and KR (Adjusted HR: 1.09 (1.01–1.17); P value: 0.022).
      Conclusions: Both baseline and follow-up history of oral calcium supplementation, but not nutritional calcium intake, was associated knee OA progression and KR.
      Tabled 1Table 1. History of taking calcium/TUMS (alone or combined with vitamin D or magnesium) in the Osteoarthritis Initiative cohort.
      From the baseline reports
      For more than last 5 yearsForup to 5 yearsWithin the past 12 monthWithin the past 30 days
      No or Not Available / Applicable--23263253
      From the follow-up reports
      1styear2nd year3rd year4th year6th year
      Didn't take21762144206419991737
      A few days per month345333300278242
      1 –3 days per week220162184147186
      4–6 days per week241263250248226
      Every day13321243125813751313
      In the baseline report, subjects were asked about “how often” they have taken calcium/TUMS (alone or combined with vitamin D or magnesium) during the3 past 12 month (and for “how many years”). They were also asked if they have taken calcium/TUMS within the past 30 days; In the 1st, 2nd, 3rd, 4th and 6th year follow-ups subjects were asked about “how often” they have taken calcium/TUMS (alone or combined with vitamin D or magnesium) during the past 30 days. ∗∗Note that the remaining subjects either refused to answer question or were missed to follow up.