Purpose: To study the effect of inhaled corticosteroid (ICS) on bone mineral density (BMD) in an observational longitudinal study.
Methods: In 1995-97, as part of the Nord-Trøndelag Health Study, Norway, 10,941 subjects aged 20 yr or more, either reporting asthma diagnosis/asthma-related symptoms or randomly selected, were interviewed, underwent spirometry and had their forearm BMD assessed. Among these, 4705 persons were invited to follow-up interview and bone densitometry in 2001; a total of 2848 subjects were eligible for analyses.
Results: Use of corticosteroids for respiratory diseases was reported by 1262 subjects, and 528 subjects had used ICS at both baseline and follow-up. The yearly loss of adjusted forearm distal BMD was higher in those reporting use of ICS at both baseline and follow-up compared to subjects without respiratory symptoms. In women the figures were 3.14 versus 2.26 mg/cm2, whilst in men they were 3.76 versus 1.92 mg/cm2 (both p<0.01). No significant association was found between loss of BMD and neither daily dose nor duration of ICS use. Reduced lung function (forced expiratory flow in 1s) was an independent risk factor for increased bone loss in both sexes.
Conclusions: ICS users had greater bone loss at the forearm compared to ICS naive persons, but no significant dose-response effect between ICS and BMD was found. Residual confounding by disease severity cannot be ruled out, but even in case of an ICS causal effect, this should have minor clinical significance in most patients using low to moderate doses of ICS.