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Depts of 1 Pulmonology, 2 Pathology and Laboratory Medicine, 6 Paediatric Pulmonology, University Hospital Groningen, 3 Dept of Epidemiology and Biostatistics, Erasmus Medical Centre, Rotterdam, 4 Dept of Paediatrics, Medical Centre, Leeuwarden, and 5 Dept of Paediatrics, Division of Paediatric Pulmonology, Isala Klinieken, Zwolle, the Netherlands
CORRESPONDENCE: M.J. Visser, Dept of Pulmonology, University Hospital Groningen, P.O.Box 30,001, 9700 RB, Groningen, the Netherlands. Fax: 31 503619320. E-mail: M.Visser@int.azg.nl
Keywords: Adrenal cortex, bone metabolism, fluticasone, height, hyperresponsiveness
Received: February 25, 2004
Accepted April 20, 2004
This study was supported by GlaxoSmithKline (the Netherlands), De Stichting Astma Bestrijding, University Hospital Groningen and the University of Groningen.
| Abstract |
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In 55 children with chronic persistent asthma, aged 610 yrs, airways hyperresponsiveness (AHR) and systemic side-effects (height, bone parameters and adrenal cortical function) were assessed at predetermined intervals in a double-blind prospective 2-yr study.
AHR improved after 4 months treatment with 1,000 µg·day1 FP followed by 500 µg·day1, without significant differences during long-term treatment between the two approaches. Dose-dependent reduction of growth velocity, adrenal cortical function and biochemical bone turnover was found during therapy with 1,000 and 500 µg·day1 FP when compared with 200 µg·day1.
In conclusion, doses of 1,000 and 500 µg·day1 fluticasone propionate are associated with marked reductions of growth velocity, bone turnover and adrenal cortical function. However, conventional doses (
200 µg·day1 fluticasone propionate) appear to be safe in the long-term management of childhood asthma. From a safety point of view, high doses of fluticasone propionate should only be prescribed in exceptions, e.g. in persistent severe asthma.
Inhaled corticosteroids (ICS) are the cornerstone of asthma treatment. As these drugs are highly effective in improving symptoms, lung function, airways hyperresponsiveness (AHR) and quality of life in asthmatic children, they are recommended as controller therapy in all but the mildest forms of childhood asthma 14.
Although current guidelines advise treatment with ICS indoses
400 µg·day1, it has been advocated to start ICS therapy in childhood asthma with a high dose, in order to reduce airway inflammation powerfully, and to subsequently taper off to the lowest effective dose ("step-down" strategy) 4. It is also advocated to double the dose of ICS when asthma deteriorates. As a result, high dosages of ICS are frequently used, but very limited data is available on the effects and side-effects of high-dose ICS therapy in children 5. In a previous report on the same study, the current authors have shown an initial improvement in AHR in children with asthma during high-dose fluticasone propionate therapy (FP; 1,000 µg·day1 for 2 months, followed by 2 months of 500 µg·day1) compared with children treated witha constant dose of 200 µg·day1 FP 6. When the dose of FP was tapered to 100 µg·day1, no differences were found between asthmatic children treated with this step-down approach and children using 200 µg·day1 FP during the full1-yr follow-up. Thus, the step-down approach does not appear to be superior to a constant-dose approach of FP in children with chronic persistent asthma.
Concerns regarding the adverse effects of ICS on growth in children have been relieved by recent reports showing normal height during ICS treatment for 46 yrs and normal final height at adult age after long-term ICS therapy (budesonide, mean dose 400 µg·day1) 7, 8. Although effects of ICS on bone mineral density (BMD) in adults have been described, studies in children did not demonstrate reduction of BMD during ICS treatment 7, 913. Even during long-term treatment, therefore, ICS appear to be safe, but clinically relevant systemic side-effects have been reported anecdotally 1417.
The current report deals with the second year of follow-up of a previously published double-blind study that was designed to compare effects of different dosage schedules of FP during 2-yr follow-up in these asthmatic children, focusing on systemic side-effects.
| Methods |
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Outcome measurements
Expiratory flow/volume curves were obtained with a Jaeger Masterlab pneumotachograph (Eric Jaeger GmbH, Würzburg, Germany) according to the guidelines of the European Respiratory Society 19. AHR to methacholine was measured using a dosimeter method as published previously 18. Patients kept symptom and peak flow diaries during the study. These data have been published previously and will not be reported here 6.
Height was measured at predetermined intervals (fig. 1b
) by trained technicians, using a calibrated Harpenden stadiometer (Holtain, Crymych, UK). Growth velocity in cm·yr1 was calculated from changes in height over time. Bone age of the left hand was determined at randomisation and after 1 and 2 yrs using the Tanner and Whitehouse method by a single blinded investigator 20. Tanner's pubertal stages were scored at each follow-up visit 21. BMD of the spine was measured by dual energy X-ray absorption from L1 to L4, using a Hologic QDR-4500 C Elite (Hologic, Bedford, MD, USA) 22.
Serum osteocalcin and amino-terminal propeptide of type-1 procollagen (P1NP), markers of bone formation, were measured using the immunoradiometric assay of Medgenix-H-Ost (Fleurus, Belgium) and radio-immunosorbent assay kit of Orion Diagnostica (Espoo, Finland), respectively. Urinary deoxypyridinoline (Dpyr) and pyridinoline (Pyr), products of bone degradation, were analysed for calcium and creatinine with a Chemistry Analyser (Merck Mega, Darmstadt, Germany) and for Dpyr and Pyr by high-performance liquid chromatography. Urinary excretion of Dpyr and calcium was corrected for urinary creatinine.
Total cortisol metabolite excretion was measured using 24 h urine (i.e. urine collected 24 h before) at preset visits (fig. 1b
) by gas/liquid chromatography as described previously 23. The following major metabolites were determined: tetrahydrocortisone, tertahydrocortisol, allotetrahydrocortisol,
-cortol,
-cortolone, ß-cortol and ß-cortolone.
Statistical analysis
Comparisons between and within both treatment groups across time points were performed by a linear mixed model. These comparisons were made both when differences in FP doses between groups were large (first months of the study) and when they were small (fig. 1a
). Two-tailed p-values of p<0.05 and 0.05<p<0.1 were considered to be statistically significant.
| Results |
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Growth velocity
Growth velocity was similar in the two groups at the start of the study (fig. 2d
). A significant dose-dependent negative effect on growth velocity appeared after 2 months treatment (1,000 µg·day1 FP versus 200 µg·day1 FP). After tapering off 1,000 µg·day1 FP, growth velocity increased when compared with the constant-dose group, which was significant at 6 months (200 µg and 100 µg FP versus 200 µg) and borderline significant at 4 and 8 months treatment (500 and 100 µg·day-1 FP versus 200 µg·day-1 FP, respectively). After 1 yr of treatment, growth velocity was significantly higher in the step-down group than in the constant-dose group (100 µg·day1 FP versus 200 µg·day1 FP), but this difference had disappeared at the end of the 2-yr treatment period.
Bone markers
Serum osteocalcin levels did not significantly differ between groups at randomisation (fig. 3a, b and c
). Children treated with 1,000 and 500 µg·day1 FP had significantly lower serum osteocalcin levels than children treated with 200 µg·day1 FP (fig. 3a
). When both groups used 200 µg·day1 FP (at the 6-month visit) or 200 µg and 100 µg·day1 FP (at the 8-month visit), serum osteocalcin levels were similar. Thereafter, osteocalcin levels increased during the 100 µg·day1 FP treatment, whereas they remained stable in the group using 200 µg·day1 FP constantly, which resulted in significantly higher osteocalcin levels in the step-down group (100 µg·day1 FP). Both serum P1NP and the urinary Dpyr levels decreased significantly during treatment with 1,000 and 500 µg·day1 FP compared with 200 µg·day1 FP (fig. 3b and c
). After 12 and 18 months treatment, a significantly higher P1NP level was present in the step-down group (100 µg·day1 FP) compared with the constant-dose group (200 µg·day1 FP; fig. 3b
), which became similar after 24 months. Urinary Dpyr levels in the step-down group (100 µg·day1 FP) were only significantly higher after 18 months treatment when compared with the constant-dose group (200 µg·day1 FP; fig. 3b and c
).
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Bone mineral density
BMD was similar at baseline, 1-yr and 2-yr treatment in both groups and changes between visits and between groups were not significant (fig. 3d
).
24-h urinary cortisol metabolite excretion
After randomisation, urinary cortisol metabolite excretion was significantly lower during treatment with 1,000 and 500 µg·day1 FP when compared to 200 µg·day1 FP (fig. 2b
). No further significant differences were found between the groups.
| Discussion |
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During the later stages of the study, when the dose of FP was
200 µg in both treatment groups, there were no between-group differences in terms of safety parameters. Standing height, growth velocity, serum P1NP, urinary Dpyr excretion, BMD and adrenal function as assessed by cortisol metabolite excretion were all comparable between groups atthe end of the study (figs 2 and 3![]()
). Moreover, most parameters did not change from baseline, when no ICS were used for a maximum of 8 weeks, to the end of the study in thegroup using a constant dose of 200 µg·day1 FP (figs 2 and 3![]()
). These observations are in accordance with earlier work showing that maintenance treatment with a regular and constant dose of ICS, i.e. 200 µg·day1 FP in the current study, has no systemic side-effects on bone turnover, height and adrenal cortical function 2429.
Two parameters of bone metabolism did not follow this pattern. Initially, serum levels of osteocalcin, a parameter of bone formation, were lower in the step-down group when doses of 1,000 and 500 µg·day1 FP were used, but increased when the FP dose was tapered off to 100 µg·day1 to significantly higher levels than those in the constant-dose group (fig. 3a
). Until now, no studies have examined the effects of different dosages of ICS on osteocalcin levels inchildren. Although one retrospective study and one nonrandomised open study showed reduced osteocalcin levels during ICS therapy, two randomised clinical trials showed no effect of beclomethasone in doses
400 µg·day1 or 200 µg·day1 FP on serum osteocalcin 3033. The relevance of the dose-dependent effects of inhaled FP on serum osteocalcin levels observed in this study is unclear (fig. 3a
). Nevertheless, it is not reflected in effects on BMD, which remained stable throughout the study (fig. 3d
). The current authors' results, like others, suggest that serum osteocalcin and BMD represent different phases of bone metabolism, with biochemical bone markers reflecting continuous remodelling and BMD reflecting long-term structural changes 33.
The current study clearly shows a negative direct effect ofhigh-dose FP on biochemical bone turnover parameters, which abate after treatment with lower doses for
2 yrs. Throughout the study, BMD did not differ significantly between the two study arms, suggesting no detrimental effect of overall long-term use of FP on BMD in asthmatic children. Within the group treated with a constant dose of 200 µg·day1 FP, a trend towards a decrease in BMD in the first year was observed, which became statistically significant in the second year of treatment. This result should be interpreted with caution. It contrasts with the Childhood Asthma Management Program study where 200 µg of budesonide·day1, given during 46 yrs, did not affect BMD 7.
Moreover, the current study was not double-blinded with placebo and other long-term studies with FP in children are lacking. Finally, the step-down group used a higher cumulative dose of FP during the first year (120,000 µg) than the constant-dose group (72,000 µg); nevertheless, changes in BMD in the step-down group were not significant. Thus, there were no significant differences in BMD changes over time between the two study groups and, if anything, a worsening of BMD only in the group treated with the overall lowest dose. Clearly, further long-term studies are needed toevaluate effects of low-dose ICS treatment on BMD in children.
The most prominent finding of the current study is themarked negative effects of high-dose FP (1,000 and 500 µg·day1) on growth velocity and adrenal cortical function (fig. 2
) and on biochemical markers of bone turnover and BMD (fig. 3
). A reassuring finding is that these effects areshort-lived and fully reversible when the dose of FP is tapered down. Furthermore, prolonged use of ICS may provide less negative effects than short-term therapy 34. In any case, the magnitude of the observed findings warrants a note of caution because it suggests a clear potential for clinically relevant side-effects if high dosages of FP are continued for prolonged periods of time. Indeed, clinically relevant growth suppression and adrenal failure have been described anecdotally in children receiving high-dose FP therapy 15, 3538.
In conclusion, the current study shows that maintenance therapy with inhaled fluticasone propionate in dosages of
200 µg·day1 appears to be safe in the long-term management of childhood asthma. Nevertheless, marked reduction of growth velocity, biochemical bone turnover and adrenal cortical function occurs during treatment with high dosages of inhaled fluticasone propionate. Given the current findings that high-dose fluticasone propionate therapy is no more effective than a "regular dose" and that it may cause clinicallysignificant side-effects, it is proposed that high dosages of inhaled fluticasone propionate should be prescribed for exceptions, e.g. in persistent severe asthma. These results provide a guideline to use the lowest effective dose ofinhaled corticosteroids in order to prevent systemic side-effects.
| Acknowledgements |
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| References |
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G Russell Very high dose inhaled corticosteroids: panacea or poison? Arch. Dis. Child., October 1, 2006; 91(10): 802 - 804. [Full Text] [PDF] |
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A. D. Smith, J. O. Cowan, K. P. Brassett, G. P. Herbison, and D. R. Taylor Use of Exhaled Nitric Oxide Measurements to Guide Treatment in Chronic Asthma N. Engl. J. Med., May 26, 2005; 352(21): 2163 - 2173. [Abstract] [Full Text] [PDF] |
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