IN RESPONSE:
We appreciate Dr. Sutherland's careful review of our meta-analysis. Dr. Sutherland questions whether we considered pooled data from 3 studies reported in a previous meta-analysis (1), which we referred to in our paper. We included only 1 of the 3 studies (2) in our analysis. One of the studies (3) included in this previous meta-analysis was excluded by our predetermined criteria; this study included patients with asthma. The third study by Derenne (4) was not included in our analysis because the data were reported only in abstract form and could not be extracted from the original abstract. In addition, the author could not be contacted.
We included data from the study by Pauwels and coworkers (5) as mean rather than median values because the variant of the t-test used in meta-analyses is robust to large deviations from normality (6). In this study, the baseline distributions had very low coefficients of variation in both groups (0.17 and 0.16), suggesting that outliers contributed to the skewness in change from baseline. When a sample from a symmetrical population contains outliers, the sample median is a better estimate of the population mean than the sample mean. We were unable to obtain data from the authors to verify our assumption. We believed it was necessary to include this very large study (1277 patients) in our meta-analysis because it met our inclusion criteria and favored a treatment effect. If we reanalyze our data with this study excluded, however, the overall treatment effect remains nonsignificant (–4.98 mL/y; P = 0.11). Sensitivity analysis demonstrated that the difference between the actual means and the reported medians would need to be extraordinarily large (> 2-fold) to change the statistical conclusions of our model.
We made an error in analyzing the treatment effect reported by Vestbo and associates (7) (3.1 mL/y rather than –3.1 mL/y). This error, however, did not alter the conclusions of our analysis because the effect on our results is minor. Using the corrected value, the overall treatment effect is –5.31 ± 3.0 mL/y (P = 0.08) as opposed to the originally reported –5.0 ± 3.2 mL/y (P = 0.11).
Our meta-analysis confirms the Global Initiative for Chronic Obstructive Lung Disease Workshop's opinion that inhaled corticosteroids do not modify the long-term decline in lung function of COPD (8). We agree with Dr. Sutherland that patient-centered measures of outcome, such as respiratory-related quality of life, are more important than FEV1 in assessing the value of interventions to improve the well-being of patients with COPD. Pending future investigations, clinicians should not prescribe inhaled corticosteroids with the belief that this therapy will attenuate the decline in FEV1.
1. van Grunsven PM, van Schayck CP, Derenne JP, Kerstjens HA, Renkema TE, Postma DS, et al. Long term effects of inhaled corticosteroids in chronic obstructive pulmonary disease: a meta-analysis Thorax. 1999;54:7-14. [PMID: 10343624].[Abstract/Free Full Text]
2. Renkema TE, Schouten JP, Koeter GH, Postma DS. Effects of long-term treatment with corticosteroids in COPD Chest. 1996;109:1156-62. [PMID: 8625660].[Abstract/Free Full Text]
3. Kerstjens HA, Brand PL, Hughes MD, Robinson NJ, Postma DS, Sluiter HJ, et al. A comparison of bronchodilator therapy with or without inhaled corticosteroid therapy for obstructive airways disease. Dutch Chronic Non-Specific Lung Disease Study Group N Engl J Med. 1992;327:1413-9. [PMID: 1357553].[Abstract]
4. Derenne JP. Effects of high dose inhaled beclomethasone on the rate of decline in FEV1 in patients with chronic obstructive pulmonary disease: results of a 2 years prospective multicenter study [Abstract] Am J Respir Crit Care Med. 1995;151:463.
5. Pauwels RA, Lofdahl CG, Laitinen LA, Schouten JP, Postma DS, Pride NB, et al. Long-term treatment with inhaled budesonide in persons with mild chronic obstructive pulmonary disease who continue smoking. European Respiratory Society Study on Chronic Obstructive Pulmonary Disease N Engl J Med. 1999;340:1948-53. [PMID: 10379018].[Abstract/Free Full Text]
6. Riegelman RK, Hirsch RP. Studying a Study and Testing a Test. Boston: Little, Brown; 1989:254-5.
7. Vestbo J, Sorensen T, Lange P, Brix A, Torre P, Viskum K. Long-term effect of inhaled budesonide in mild and moderate chronic obstructive pulmonary disease: a randomised controlled trial Lancet. 1999;353:1819-23. [PMID: 10359405].[Medline]
8. Pauwels RA, Buist AS, Calverley PM, Jenkins CR, Hurd SS. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary Am J Respir Crit Care Med. 2001;163:1256-76. [PMID: 11316667].[Free Full Text]
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