Validity of self-reported osteoporosis in mid-age and older women

Abstract

Summary

The validity of self-reported osteoporosis is often questioned, but validation studies are lacking. We validated self-reported prevalence and incidence of osteoporosis against self-reported and administrative data on medications. The concurrent validity was moderate to good for self-reported prevalent osteoporosis, but only poor to moderate for self-reported incident osteoporosis in mid-age and older women, respectively. Construct validity was acceptable for self-reported prevalent but not for incident osteoporosis.

Introduction

The validity of self-reported osteoporosis is often questioned, but validation studies are lacking. The aim was to examine the validity of self-reported prevalence and incidence of osteoporosis against self-reported and administrative data on medications.

Methods

Data were from mid-age (56–61 years in 2007) and older (79–84 years in 2005) participants in the Australian Longitudinal Study on Women’s Health. Self-reported diagnosis was compared with medication information from (1) self-report (n _mid = 10,509 and n _old = 7,072), and (2) pharmaceutical prescription reimbursement claims (n _mid = 6,632 and n _old = 4,668). Concurrent validity of self-report was examined by calculating agreement, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Construct validity was tested by examining associations of self-reported diagnosis with osteoporosis-related characteristics (fracture, weight, bodily pain, back pain, and physical functioning).

Results

Agreement, sensitivity and PPV of self-reported prevalent diagnosis were higher when compared with medication claims (mid-age women: kappa = 0.51, 95% confidence interval [CI] = 0.46–0.56; older women: kappa = 0.65, 95% CI = 0.63–0.68) than with self-reported medication (mid-age women: kappa = 0.41, 95% CI = 0.37–0.45; older women: kappa = 0.57, 95% CI = 0.55–0.59). Sensitivity, PPV and agreement were lower for self-reported incident diagnosis (mid-age women: kappa = 0.39, 95% CI = 0.32–0.47; older women: kappa = 0.55, 95% CI = 0.51–0.61). Statistically significant associations between self-reported diagnosis and at least four of five characteristics were found for prevalent diagnosis in both age groups and for incident diagnosis in older women.

Conclusions

The concurrent validity was moderate to good for self-reported prevalent osteoporosis, but only poor to moderate for self-reported incident osteoporosis in mid-age and older women, respectively. Construct validity was acceptable for self-reported prevalent but not for incident osteoporosis.

Appendix

Table 5 Overview of osteoporosis medication claims in the Pharmaceutical Benefits Scheme (PBS)

Summary of indications for PBS benefits (more details can be found on http://www.pbs.gov.au/browse/body-system):

• 1. Treatment as the sole PBS-subsidised anti-resorptive agent for corticosteroid-induced osteoporosis in a patient currently on long-term (at least 3 months), high-dose (at least 7.5 mg/day prednisolone or equivalent) corticosteroid therapy with a BMD T-score of −1.5 or less

• 2. Treatment as the sole PBS-subsidised anti-resorptive agent for osteoporosis in a patient aged 70 years or older with a BMD T-score of −3.0 or less

• 3. Treatment as the sole PBS-subsidised anti-resorptive agent for established osteoporosis in patients with fracture due to minimal trauma

• 4. For preservation of BMD in patients on long-term glucocorticoid therapy where patients are undergoing continuous treatment with a dose equal to or greater than 7.5 mg of prednisone or equivalent per day. Prescribers need to demonstrate that the patient has been on continuous therapy for 3 months or more and demonstrate that the patient is osteopenic (bone mineral density T-score of less than −1.0)

• 5. One of following three indications:

• 5.1. Initial treatment, as the sole PBS-subsidised agent, by a specialist or consultant physician, for severe, established osteoporosis in a patient with a very high risk of fracture who:

• (a) Has a bone mineral density (BMD) T-score of −3.0 or less; and

• (b) Has had two or more fractures due to minimal trauma; and

• (c) Has experienced at least one symptomatic new fracture after at least 12 months continuous therapy with an anti-resorptive agent at adequate doses

• 5.2. Initial treatment, as the sole PBS-subsidised agent, by a specialist or consultant physician, for severe, established osteoporosis in a patient with a very high risk of fracture who was receiving treatment with teriparatide prior to 1 May 2009

• 5.3. Continuing treatment for severe established osteoporosis where the patient has previously been issued with an authority prescription for this drug

• 6. Treatment for established osteoporosis in patients with fracture due to minimal trauma.

Additional notes:

Anti-resorptive agents in established osteoporosis include alendronate sodium, risedronate sodium, denosumab, disodium etidronate, raloxifene hydrochloride, strontium ranelate and zoledronic acid

Minimal trauma fractures must have been demonstrated radiologically and the year of plain X-ray or CT scan or MRI scan must be documented in the patient's medical records when treatment is initiated

A vertebral fracture is defined as a 20% or greater reduction in height of the anterior or mid portion of a vertebral body relative to the posterior height of that body, or, a 20% or greater reduction in any of these heights compared to the vertebral body above or below the affected vertebral body

SERM Selective Estrogen Receptor Modulator