Skeletal status assessed by quantitative ultrasound at the calcaneus in females with bronchial asthma on prolonged corticosteroid therapy

Abstract

Objective: The aim of the study was to assess skeletal status in bronchial asthma female patients after long-term oral corticosteroid (CS) therapy. Methods: Eighty-two female patients (25 with and 57 without fractures; mean age 58.0 ± 7.8 years) were compared with 999 females (821 controls without fractures, mean age 58.6 ± 7.2 years and 178 females with previous osteoporotic fractures, mean age 57.8 ± 7.1 years). Mean age and years since menopause did not differ between patients and controls. The duration of CS therapy was 8.4 ± 7.3 years, and daily mean dose equivalent to prednison was 8.8 ± 3.5 mg. Skeletal status was evaluated by quantitative ultrasound (QUS) measurements at the heel using the Achilles system (Lunar, USA) which measures speed of sound (SOS (m/s)) and Broadband Ultrasound Attenuation (BUA (dB/MHz)). The Achilles software also calculates a stiffness index (SI (%)). The precision expressed using the root mean square coefficient of variation (RMS_CV%) was: 0.26% for SOS, 4.37% for BUA, and 2.13% for SI. Results: Patients (all, with and without fractures) had significantly lower QUS values than controls without fractures and their values did not differ significantly from controls with fractures. Controls with fractures had significantly lower QUS values than controls without fractures. There was no difference between patients with and without fractures. The duration of the therapy did not influence skeletal variables in any group. Receiver operating characteristic curve (ROC) analysis was performed to assess the discriminatory capability of calcaneal QUS for CS-treated patients by calculating the area under the ROC curve (AUC). AUCs were: 0.70 for SOS, 0.68 for BUA and 0.70 for SI. Conclusions: In females with bronchial asthma on prolonged CS therapy, skeletal status is affected but does not differ from controls with fractures therefore CS therapy seems to be a risk factor for osteoporotic fracture. Calcaneal QUS measurements can be a useful tool in the assessment of CS bone-side effects.