Effect of inhaled corticosteroid on bone density in asthmatic patients: a pilot study

We investigated the effect of long-term inhaled (ICS) and oral corticosteroid (OCS) therapy on bone density by using single and dual photon absorptiometry. We studied a group of five asthmatic patients who inhaled an average of 326 micrograms/day of beclomethasone dipropionate equivalents for 50 months (range 36 to 62 months) and a control group of five asthmatic patients on OCS, who used 12.5 mg of prednisone equivalents daily for an average of 57 months (range 22 to 120 months). The ICS group's average bone densities relative to age and sex-matched controls were 99.7%, 99.2%, and 90.0% for the radius, spine, and hip, respectively. The OCS group's average bone densities relative to age-matched and sex-matched controls were 94.4%, 85.4%, and 84.5% for the identical sites. A dose-response relationship between the cumulative dose of ICS and the relative bone density was absent in the study group but demonstrable in the control group of asthmatics on long-term OCS therapy. These results suggest that ICS therapy, unlike OCS, may not induce bone loss at the doses used by our subjects. Further research is required to determine whether a single user of ICS with unusually low bone density measurements represents a biologic variant, or a subgroup of patients who are especially sensitive to the systemic effects of ICS.