Published ahead of print on October 9, 2003, doi:10.1164/rccm.200305-640OC
© 2004 American Thoracic Society Inhaled and Nasal Corticosteroid Use and the Risk of FractureDivisions of Clinical Epidemiology and Endocrinology, Royal Victoria Hospital, McGill University Health Centre; Department of Epidemiology and Biostatistics and of Medicine, McGill University; Department of Respiratory Medicine, Mount Sinai Hospital; and Division of Respiratory Medicine, McGill University Health Centre, Montreal, Quebec, Canada Correspondence and requests for reprints should be addressed to Samy Suissa, Ph.D., Division of Clinical Epidemiology, Royal Victoria Hospital, 687 Pine Avenue West, Ross 4.29, Montreal, PQ, H3A 1A1 Canada. E-mail: samy.suissa{at}clinepi.mcgill.ca
Studies of the risk of fracture associated with inhaled corticosteroids are inconclusive and are limited to short-term effects. We assessed whether long-term use increases this risk. We conducted a case control study nested within a population-based cohort of all Quebec elderly dispensed respiratory medications and followed for at least 4 years during 1988–2001. There were 9,624 new cases of fracture of the hip or upper extremities and 191,622 age-matched control subjects (mean age of 81 years). The rate of any such fracture for current inhaled corticosteroid use was not elevated (rate ratio [RR], 0.97; 95% confidence interval [CI], 0.92–1.03). For upper-extremity fracture, the rate increased by 12% (RR, 1.12; 95% CI, 1.04–1.19) with every 1,000-µg increase in the daily dose of inhaled corticosteroids, but not for hip fracture (RR, 0.97; 95% CI, 0.88–1.07). Among subjects followed for over 8 years, the rate of hip fracture was only elevated with daily doses of more than 2,000 µg of inhaled corticosteroids (RR, 1.61; 95% CI, 1.04–2.50). The rate was not elevated at any dose of nasal corticosteroids. In conclusion, the long-term use of inhaled and nasal corticosteroids at the usual recommended doses is not associated with a risk of fracture in older patients with respiratory disease.
Key Words: asthma • cohort studies • chronic obstructive pulmonary disease • glucocorticoids • osteoporosis Inhaled corticosteroids are effective drugs for the treatment of asthma, improving symptoms and reducing morbidity and mortality, even at low doses (1–6). They are now also being used to treat chronic obstructive pulmonary disease (7). Nasal corticosteroids are increasingly becoming first-line therapy for the regular control of allergic rhinitis (8). The consumption of these topical corticosteroids has consequently risen considerably since the 1980s (9–11) and is expected to rise further following the recommendations in several countries for their introduction earlier in the course of disease and at higher doses than ever in the past (12–14). Safety concerns, including osteoporosis and fractures, have been expressed in relationship to the long-term use of topical corticosteroids (15). Clinical studies have shown that accelerated bone resorption occurs at all doses (16–18). Furthermore, several studies have reported dose-dependent decreases in bone density (19–21). However, whether these actually translate to fractures is unknown but is of great consequence as people age. Indeed, fracture incidence, morbidity, and mortality rise significantly after the age of 70 years (22–26). To date, four observational studies have attempted to associate fractures with inhaled corticosteroids. The first, which found no association with hip fracture risk, had a study size too small to estimate the risk with precision (27). The second study, using a cohort of patients from the United Kingdom General Practice Research Database, found a small, albeit not significant, increase in risk for hip fracture (rate ratio [RR], 1.20; 95% confidence interval [CI], 0.99–1.45) for inhaled corticosteroid use relative to bronchodilator use, although the follow-up was short at 1.7 years (28). Another study using the General Practice Research Database found an increase in the risk of hip fracture (RR, 1.19; 95% CI, 1.10–1.28) for inhaled corticosteroid use relative to no inhaled corticosteroid use, mostly among subjects without asthma or chronic obstructive pulmonary disease, but with a longer follow-up at a median of 2.7 years (29). The last was a cohort study from Ontario, Canada, that found no increase in the risk of hip fracture (RR, 0.92; 95% CI, 0.75–1.12) for inhaled corticosteroid use relative to the use of proton pump inhibitors, although the follow-up was short at less than 1 year (30). Thus, to date, the epidemiologic studies assessing the risk of fracture associated with inhaled corticosteroids are inconclusive, and none has evaluated the effect of longer term use of these drugs. In this study, we assessed whether and at what dose long-term inhaled and nasal corticosteroid use increases the risk of fracture among older patients dispensed respiratory medications.
Source of Data We used the health databases of the Régie de l'assurance maladie du Québec. The databases contain information on demographics, all medical services rendered, along with the diagnostic code of the service (ICD-9 code) and, for people aged 65 years or older, all outpatient prescription medications dispensed.
Study Design
Case Definition
Control Subjects
Corticosteroid Exposure
Covariates
Statistical Analysis
The source population contained 352,697 people, of whom 202,007 belonged to the respiratory cohort defined by three or more prescriptions for respiratory drugs in any 1-year period. After excluding 61,208 subjects with less than 4 years of follow-up and 7,773 with a previous fracture of the hip, upper extremities, or vertebrae, the cohort included 133,026 subjects. We identified 9,624 new cases of fracture of the hip or upper extremities that occurred during follow-up and selected 191,622 age-matched control person-moments from the risk sets. Of these, 3,326 are fractures of the hip, and 6,298 are fractures of the upper extremities. Cases and control subjects were 81 years of age at the index date. Table 1 indicates that the cases were more likely to be women and had experienced more other types of fracture during the prior 4 years than control subjects. They were also more likely to use central nervous system drugs within 90 days of the index date. The majority of inhaled corticosteroid canisters identified during the 4-year period were of beclomethasone (63%), budesonide (19%), or fluticasone (17%), whereas for nasal steroids, beclomethasone (39%) and fluticasone (30%) formed the largest share of the prescriptions dispensed, with budesonide, flunisolide, and triamcinolone accounting approximately equally for the rest.
Table 2 presents the crude and adjusted matched RRs of fracture of the hip or upper extremity for use of inhaled and nasal corticosteroids. It indicates that the rate of fracture for current use of inhaled and nasal corticosteroids, as well as for use at any time during the 4-year time window, is no different than for nonuse during this period. The RRs were also similar for the individual corticosteroid preparations.
Table 3 indicates that the mean daily doses of inhaled corticosteroids are slightly higher for cases than control subjects. The log-linear dose–response model shows that after adjustment for the covariates, the rate of fracture increases by 6% (RR, 1.06; 95% CI, 1.01–1.12) for every 1,000-µg increase in the daily dose of inhaled corticosteroids (beclomethasone-equivalent units). For doses of inhaled corticosteroids above 2,000 µg per day, the adjusted RR of fracture is 1.11 (95% CI, 0.86–1.43). For nasal corticosteroids, no increase with increasing doses is observed. The RRs were similar among users and nonusers of oral corticosteroids (data not shown). The fracture risk increased by 2% (RR, 1.02; 95% CI, 1.01–1.03) for each 1,000 mg of oral corticosteroids (prednisone-equivalent units) dispensed over the prior 4 years.
Table 4 presents the RRs separately for fractures of the hip and for fractures of the upper extremities in relationship to inhaled corticosteroid use. The RRs for hip fracture are similar to the overall RRs. For fractures of the upper extremities, the RRs are slightly higher. The rate of these fractures increases significantly by 12% (RR, 1.12; 95% CI, 1.04–1.19) for every 1,000-µg increase in the daily dose of inhaled corticosteroids (beclomethasone-equivalent units).
Further analyses were performed in the subgroup of 3,701 cases and 73,858 control subjects, with at least 8 years of follow-up in the cohort. Most RRs were no different than unity. Only the use of more than 2,000 µg of inhaled corticosteroids per day for an average of 6 years was associated with an elevated risk of fracture (RR, 1.61; 95% CI, 1.04–2.50). This means that 58 subjects (95% CI, 24–1,767 subjects) would need to be treated with more than 2,000 µg of inhaled corticosteroids per day for 6 years to result in one extra fracture. The log-linear continuous dose–response analysis showed no definite increase (RR, 1.08; 95% CI, 0.98–1.20).
We have shown with this population-based nested case control study that the use of inhaled and nasal corticosteroids is generally not associated with an increased risk of fracture of the hip or upper extremities in older patients dispensed respiratory medications when used at the usual recommended doses over a 4-year period. There was, however, a small increase in overall fracture risk of 6% per 1,000 µg increase in mean daily dose, which was of borderline statistical significance. This increase was due entirely to an increase in the risk of an upper extremity fracture, which increased by 12% per each additional 1,000 µg of inhaled corticosteroid per day in beclomethasone-equivalent units. The increased risk was only apparent at daily doses of more than 1,000 µg, doses now required less frequently with the advent of effective combination therapy with long-acting inhaled ß-agonists added to inhaled corticosteroids (39). The higher dose users of inhaled corticosteroids, who were dispensed the beclomethasone equivalent of over 1,500 µg per day, represented only 5% of all users of inhaled corticosteroids. A slight increase in risk of hip and upper extremity fracture combined appeared in the two strata that formed this high-dose group, with RR estimates of 1.08 and 1.11, both with confidence intervals that largely include 1. With the actual number of cases and control subjects obtained, the study had 90% power to detect a RR of 1.3 or higher for doses of inhaled corticosteroid above 1,500 µg per day and a RR of 1.5 or higher for doses above 2,000 µg per day. The major strength of this study is its size, with over 9,500 cases and 191,000 control subjects selected from all subjects over 65 years of age in the population who were dispensed drug treatment for chronic respiratory disease between 1988 and 2001. Our study assessed the effect of inhaled corticosteroid use over at least a 4-year period. A crucial facet of our study is the completeness of drug information collected in the Régie de l'assurance maladie du Québec database that allowed us to separate the effects of oral corticosteroids from that of the inhaled variety and to estimate daily doses over a long period of time. This information was essential in permitting an accurate estimation of the safety thresholds of inhaled corticosteroid use and in eliminating confounding by use of oral corticosteroids. Observational studies such as ours have limitations. Fractures occurring outside the province are not always included in the Régie de l'assurance maladie du Québec database, possibly inducing selection bias. However, the gravity of a hip fracture makes it unlikely that such an event is not recorded as the Régie de l'assurance maladie du Québec reimburses, in part, health-related expenses incurred outside the province. We also selected, as the outcome, fracture of the hip and upper extremities, and not vertebral fractures, to avoid underestimating the risk estimate because the latter do not always result in a medical intervention and would thus not be systematically recorded in the databases. Fractures of the hip and upper extremities have been validated previously in this database with 99.2% and 92.7% sensitivity (40). The measure of exposure, based on dispensed inhaled corticosteroids, is a common limitation of databases studies as it may not represent actual intake or even actual use. This limitation linked to low compliance and poor inhaler technique may have underestimated the risk. However, it is unlikely that subjects dispensed over 1,500 µg per day of inhaled corticosteroids over 4 years are not using these drugs. Another limitation arises from our restriction of the exposure period to the 4-year span before the index date. This was necessary, as prescription drug data were only available starting at 65 years of age. As a result, the use of oral corticosteroids before age 65 that may have affected bone mass could not be adjusted for. Nevertheless, the effects were similar among subjects who used oral steroids during the year before the index date and those who did not. Moreover, besides the cumulative use of oral corticosteroids, we also adjusted for the degree of severity of respiratory disease. Although we adjusted the RRs for several known risk factors, we did not have access to some potential confounding factors such as smoking, physical activity, or obesity. Patients with respiratory disease are more likely to be smokers and tend to have lower body mass index, both of which are risk factors for fracture. Physical activity, usually limited in patients with respiratory problems for whom inhaled corticosteroids are indicated, is associated with osteoporosis and the risk of fractures (32). We do not believe this to be a problem, however, as these associations are weak and thus are unlikely to affect our results in any substantial way. The one cohort study that specifically measured physical activity found no difference in physical activity between users and nonusers of inhaled corticosteroids (27). The implications of our results for the treatment of respiratory disease are important. The fact that long-term use of inhaled corticosteroids does not appear to be associated with an increased risk of hip or upper extremity fracture, except at very high doses, suggests that the doses corresponding to the current treatment guidelines are safe.
S.S. has no declared conflict of interest; M.B. has no declared conflict of interest; R.K. has no declared conflict of interest; P.E. has been on the advisory boards, and has received speaker fees over the last three years, from GlaxoSmithKline (Canada), AstraZeneza (Canada), and Merck Frosst (Canada), compensation totaled approximately $10,000 Cdn from Merck Frosst (Canada). The authors thank M. Jacques Barry of the Régie de l'assurance maladie du Québec for his assistance in obtaining the data and Ms. Sophie Dell'Aniello for assistance in data analysis.
Supported by grants from the Canadian Institutes of Health Research and GlaxoSmithKline, a Distinguished Investigator award from the Canadian Institutes of Health Research (S.S.), and an infrastructure grant for the McGill Pharmacoepidemiology Research Unit from the Fonds de la recherche en santé du Québec. This article has an online supplement, which is accessible from this issue's table of contents online at www.atsjournals.org Received in original form May 12, 2003; accepted in final form October 8, 2003
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