To explore the prevalence of osteoporosis (OP) and vertebral osteoporotic fracture (OPF) and related risk factors in patients with rheumatoid arthritis (RA).
A total of 644 patients with RA from Jan. 2010 to Oct. 2013 were recruited, anteroposterior and lateral X-rays examination of vertebral column (T5-L5) were conducted, and semi-quantity method were used as the standard for judging vertebral OPF. Meanwhile, patients' clinical and laboratory data including daily dosage of glucocorticoid, duration of glucocorticoid usage, cumulative amount dosage of glucocorticoid were recorded in details. 158 normal subjects were selected as control group.
(1)The prevalence of vertebral OPF in patients with RA was 16.6%. Bone mineral density (BMD) of all measured lumbar vertebra in RA group were markedly decreased [(0.97 ± 0.22) g/cm(2)]. The total prevalence of OP at lumbar vertebra in RA was 17.9% (81/452), which was significantly higher than that of control group (4.4%, 7/158) (P < 0.001). (2) The percentage of OP in RA patients with vertebral OPF was significantly higher than that in patients without OPF [40.6% (41/101) vs 11.4% (40/351); P < 0.001]. Patients with OPF were of older age, longer use of glucocorticoid, more cumulative amount dosage of glucocorticoid, longer disease duration, higher scores of health assessment questionnaires (HAQ) and increased ESR (P < 0.05). (3) Logistic regression analysis revealed that age (OR = 1.094, 95% CI 1.065-1.125, P < 0.001) and gender (1 = male, 2 = female) (OR = 5.600, 95% CI 2.097-15.087, P = 0.001) were the risk factors for the development of OP in RA, while body mass index (BMI) was the protective factor (OR = 0.770, 95% CI 0.696-0.853, P < 0.001). Age (OR = 1.031, 95% CI 1.009-1.053, P = 0.005) and occurrence of OP at lumbar vertebra (OR = 3.765, 95% CI 2.092-6.776, P < 0.001) were risk factors of the development of OPF in RA patients. Logistic regression analysis also showed that RA was the risk factor of OPF (OR = 4.716, 95% CI 1.987-11.192, P < 0.001), even after the adjustment of age, gender and BMI. (4) Receiver operator characteristic(ROC) curve in RA patients with OPF has found that age-OPF and daily dosage of glucocorticoid-OPF AUCROC were 0.689 and 0.636 respectively. The cut-off value in ROC curve of age and daily dose or treatment course of glucocorticoid-OPF were 54.5 years and 6.25 mg (P < 0.001) , while duration of glucocorticoid usage-OPF AUCROC was 0.685, with cut-off value in ROC of age-OPF 135 days (P < 0.001).
Prevalence of OPF in patients with RA increases remarkably. Old age and OP at spine are risk factors related to the development of OPF in patients with RA.