Osteoporosis: What are the implications of DEXA scanning 'high risk' women in primary care?

Abstract

Background. Current recommended practice for the use of dual X-ray absorptiometry (DEXA) scans in screening for osteoporosis is to concentrate on women at 'high risk'. Objective. We have applied such a screening strategy, in a general practice setting, to estimate the number of women requiring scans. Methods. A two-phase survey was carried out: (i) postal screen of clinical indicators for low bone mineral density (BMD) to define women at 'high risk'; and (ii) DEXA scanning of the sample at 'high risk' set in two general practices in North Staffordshire. Computerized general practice records were used to define a purposive sample of 1001 women, to receive the screening tool, consisting of three equal size groups (i) those with an early hysterectomy; (ii) those receiving oral corticosteroids on repeat prescription; and (iii) those on the practice cervical smear register. A random sample of women defined at 'high risk' by the screening tool were invited to have a DEXA scan. The main outcome of interest was the presence of low BMD as measured by a DEXA scanner. Results. Sixty-five out of 95 women invited (68%) agreed to undergo a DEXA scan: median age = 52 years (interquartile range 44-64 years). Twenty-nine of these 65 women (45%) were classified with low BMD (WHO criteria): 90% had densities below their age-matched mean. Extrapolating from the observed findings to the main study practice (n = 9000 total population), we estimate that 162 women would be defined at 'high risk', and, if all were offered a scan, 105 would comply and 56 would be defined with low BMD. Conclusions. Using this approach, we estimate the unmet need, in women, for DEXA scans to be 180 per 10 000 total practice population. Allowing for scan uptake, this would define ∼60 women per 10 000 total practice population with low BMD. The application of this screening strategy has identified a group of women who might benefit from treatment or prophylaxis for osteoporosis.