Background Osteoporosis (OP) risk factors (RF) in CPPD patients are not sufficiently studied, although some of these RFs may be more prevalent in CPPD pts than in general population 
Objectives To identify the input of individual RFs into OP development in pts with CPPD
Methods 64 patients with CPPD (35 males and 29 females), but without OP were included into open prospective study. CPPD was confirmed based on McCarty criteria (detection of calcium pyrophosphate crystals in the synovial fluid using polarized light microscopy and detection of chondrocalcinosis based on joint radiography or US examination). 40 pts of those had acute and/or chronic arthritis, and 24 pts had osteoarthritis with CPP crystal depositions. Mean age was 57.6±10.2 years, mean follow up – 4.85±0.96 years. Bone mass density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the forearm, lumbar spine and total hip was performed in all pts at baseline. OP was diagnosed by BMD (T-criterion ≤2,5). The following OP risk factors were evaluated in this study: sex, age >55 years for females and >65 years for males, smoking, alcohol, fractures in past medical history, fractures in parents, BMI ≤20 kg/m2, BMI ≤25 kg/m2, serum levels of calcium, magnesium, vitamin D, hypoparathyroidism (HPT), chronic kidney disease (GFR ≤60 mL/min), intake of diuretics and glucocorticosteroids (GCs), Erythrocyte sedimentation rate (ESR) >20 mm/h, C-reactive protein (CRP) >5,0 mg/L. Odds ratio (OR) (95% confidence interval, CI) was estimated for each risk factor and logistic regression analysis was performed. Statistical analysis was made using SPSS v. 11 package, p values of <0.05 were considered statistically significant.
Results OP was identified in 22 (34%) out of 64 pts with CPPD (13 males and 9 females) by the end of the study. The following factors were associated with OP: age >55 years in females (odds ratio (OR) 5.0, 95% CI; 1.021–24,49; p=0.047), age >65 years in males (OR 3.9, 95% CI 1.3–11.5; p=0.014), HPT (OR 15.38, 95% CI 1.7–137.9; p=0.015), elevated ESR (OR 3.38, 95% CI 1.14–10.0; p =0.028) and CRP (OR 6.42, 95% CI 2.05–20.05; p=.001) (Fig.1).
Only hypoparathyroidism was identified by logistic regression analysis (sensitivity-71%, specificity -82%) as OP-associated risk factor (OR 14.24, 95% CI 1.05–194.05; p=0.046) (Table 1).
Conclusions Hypoparathyroidism is the key risk factor for OP in CPPD pts. Among other risk factors chronic inflammation (ESR and CRP levels) is of highest importance.
Ross P.D. Osteoporosis: frequency, consequences, and risk factors. Archives Internal Med.1996; 156:1399–141.
Disclosure of Interest None declared