Risk factors for osteoporosis and fracture in patients attending rheumatology outpatient clinics

The utility of clinical decision tools for diagnosing osteoporosis in postmenopausal women with rheumatoid arthritis

Background

Patients with rheumatoid arthritis have a higher risk of low bone mineral density than normal age matched populations. There is limited evidence to support cost effectiveness of population screening in rheumatoid arthritis and case finding strategies have been proposed as a means to increase cost effectiveness of diagnostic screening for osteoporosis. This study aimed to assess the performance attributes of generic and rheumatoid arthritis specific clinical decision tools for diagnosing osteoporosis in a postmenopausal population with rheumatoid arthritis who attend ambulatory specialist rheumatology clinics.

Methods

A cross-sectional study of 127 ambulatory post-menopausal women with rheumatoid arthritis was performed. Patients currently receiving or who had previously received bone active therapy were excluded. Eligible women underwent clinical assessment and dual-energy-xray absorptiometry (DXA) bone mineral density assessment.

Clinical decision tools, including those specific for rheumatoid arthritis, were compared to seven generic post-menopausal tools to predict osteoporosis (defined as T score < -2.5). Sensitivity, specificity, positive predictive and negative predictive values and area under the curve were assessed. The diagnostic attributes of the clinical decision tools were compared by examination of the area under the receiver-operator-curve.

Results

One hundred and twenty seven women participated. The median age was 62 (IQR 56–71) years. Median disease duration was 108 (60–168) months. Seventy two (57%) women had no record of a previous DXA examination. Eighty (63%) women had T scores at femoral neck or lumbar spine less than -1. The area under the ROC curve for clinical decision tool prediction of T score <-2.5 varied between 0.63 and 0.76. The rheumatoid arthritis specific decision tools did not perform better than generic tools, however, the National Osteoporosis Foundation score could potentially reduce the number of unnecessary DXA tests by approximately 45% in this population.

Conclusion

There was limited utility of clinical decision tools for predicting osteoporosis in this patient population. Fracture prediction tools that include risk factors independent of BMD are needed.

Estimation of bone matrix apparent stiffness variation caused by osteocyte lacunar size and density

The role of osteocyte lacunar size and density on the apparent stiffness of bone matrix was predicted using a mechanical model from the literature. Lacunar size and lacunar density for different bones from different gender and age groups were used to predict the range of matrix apparent stiffness values for human cortical and cancellous tissue. The results suggest that bone matrix apparent stiffness depends on tissue type (cortical versus cancellous), age, and gender, the magnitudes of the effects being significant but small in all cases. Males had a higher predicted matrix apparent stiffness than females for vertebral cancellous bone (p< I0(-7)) and the difference increased with age (p =0.0007). In contrast, matrix apparent stiffness was not different between males and females forfemoral cortical bone and increased with age in both males (p < 0.0001) and females (p < 0.0364). Osteocyte lacunar density and size may cause significant gender and age-related variations in bone matrix apparent stiffness. The magnitude of variations in matrix apparent stiffness was small within the physiological range of lacunar size and density for healthy bone, whereas the variations can be profound in certain pathological cases. It was proposed that the mechanical effects of osteocyte density be uncoupled from their biological effects by controlling lacunar size in normal bone.

Is enough attention being given to the adverse effects of corticosteroid therapy?

BACKGROUND

Although the corticosteroids are valuable anti-inflammatory and immunosuppressive agents, they also possess many potential adverse effects, especially with continued use. In particular, long-term corticosteroid exposure carries a significant risk of osteoporosis.

AIM

To review the use of corticosteroids in patients presenting to the major teaching hospital in Tasmania, Australia; principally to determine whether patients receiving long-term corticosteroid therapy were being monitored for loss of bone mineral density and offered preventive therapy for osteoporosis.

METHODS

A retrospective review of the medical records for 212 consecutive patients admitted to the medical wards of the hospital over a 5-month period and receiving treatment with either oral or inhaled corticosteroids, was performed. An extensive range of demographic and clinical variables was recorded for each patient. Patients were also questioned about diet and exercise, and whether they had undergone tests for measuring bone mineral density or blood glucose.

RESULTS

The median age of the patients was 69 years (range: 15-90 years) and 58% were female. Over half (53%) of the patients were on oral corticosteroids only, with 26% using inhaled corticosteroids only, and 21% on both oral and inhaled corticosteroid therapy. The most common conditions for which patients were receiving corticosteroid therapy were asthma (37% of patients), chronic obstructive pulmonary disease (33%) and rheumatoid arthritis (17%). The most commonly used oral corticosteroid was prednisolone (93%), the median daily dose was 10 mg prednisolone equivalent, and the median duration of oral corticosteroid treatment was 50 weeks. Disregarding short courses, the median duration of oral corticosteroid treatment was 104 weeks. Almost one-third (31%) of the patients receiving oral corticosteroid treatment had been taking the equivalent of 7.5 mg prednisolone daily for at least 6 months. Only 11% of all patients on oral corticosteroids and 21% of those who had been taking oral corticosteroids for at least one year had documented evidence of bone mineral density testing being performed in the past in the hospital. Only 21% of all patients on oral corticosteroids and 31% of those who had been taking oral corticosteroids for at least one year were receiving medication for osteoporosis prevention, and only 15% of women over 45 years of age and on oral corticosteroid therapy were taking hormone replacement therapy. Only about half of the patients on long-term systemic corticosteroid therapy had either documented evidence in their hospital medical records, or were aware, of having undergone blood glucose testing in the preceding 12 months.

CONCLUSION

More attention to the prevention and monitoring of possible adverse effects of long-term corticosteroid therapy is warranted. Guidelines covering preventive measures and treatment options for corticosteroid-induced osteoporosis need to be considered routinely when using these agents.