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Evan Atlantis, PhD; Paul Fahey, MMedStat; Belinda Cochrane, MD
Author and Funding Information

From the School of Nursing and Midwifery (Drs Atlantis and Cochrane), the School of Science and Health (Dr Fahey), and the School of Medicine (Dr Cochrane), University of Western Sydney; and Campbelltown Hospital, Department of Medicine, SLHD/SWSLHD (Dr Cochrane).

Correspondence to: Evan Atlantis, PhD, Family and Community Health Research Group, School of Nursing and Midwifery, University of Western Sydney, Bldg 17, Room 17.1.14, Campbelltown Campus, Locked Bag 1797, Penrith, NSW 2751, Australia; e-mail: e.atlantis@uws.edu.au


Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Atlantis has received fees to speak at events for Eli Lilly Australia. Dr Cochrane has received speaker fees and industry sponsorship to attend national and international meetings. Dr Fahey has reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;144(3):1084-1085. doi:10.1378/chest.13-1124
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To the Editor:

We thank Dr Moullec and colleagues for their interest in, and supportive comments on, our study in this issue of CHEST.1 Generally speaking, we agree with the principle that careful consideration is needed when pooling results from individual studies included in a systematic review. However, the selection of studies is also determined by the research question(s), and our study may have had a wider focus than theirs.2 Our responses to their specific points are as follows.

First, all decisions about which exposures (risk factors), primary outcomes, and summary effect measures to use were made a priori following careful consideration, as recommended by the Centre for Reviews and Dissemination.3 For instance, we predefined clinically relevant depression and anxiety by diagnostic criteria or correlated cutoff scores for self-rated symptoms. We, and others referenced by the authors, have shown that both methods classify people with chronic diseases (COPD, diabetes, and cardiovascular disease) into clinically relevant dichotomies of depression or anxiety and are widely used for identifying probable cases in epidemiologic research.1,4,5 We acknowledge that there is room to improve diagnoses in the future, but believe that the information currently available can and should be used. In addition to their call for validation studies on depression and anxiety screening tools, we believe that more research is required to determine whether specific symptoms of depression and/or anxiety are most clinically relevant in COPD. Note that reserving meta-analyses for only those studies that use near-identical methods in near-identical participant populations would be seldom achievable in practice or else would severely limit the applicability of the results obtained.3

Second, the robustness of our meta-analysis findings was confirmed using sensitivity analysis. For instance, the sensitivity analysis presented in Table 4 and Figure 2 of our article shows that the pooled risk ratio of 1.43 (1.22-1.68) was not substantially changed after exclusion of anxiety or psychological distress studies (1.45 [1.21-1.74]) and studies in non-COPD or “healthy” populations (decreased to 1.31 [1.12-1.54]). Similarly, the sensitivity analysis we presented in Table 6 and Figure 7 shows that the pooled risk ratio of 1.69 (1.45-1.96) was similar after exclusion of three studies in populations with self-reported chronic lung disease (1.55 [1.45-1.65]). While we accept that the pattern of exacerbation risk may differ between depression and anxiety syndromes by hospital setting (inpatient vs outpatient), as yet there is insufficient reliable evidence to firmly support this hypothesis.2

Third, the statistical heterogeneity between studies in our meta-analysis models was mostly a result of variation in the degree of difference rather than in an opposing direction of risk. In other words, although effect estimates from most of the individual studies varied in size, they were consistently > 1, indicating increased risk.

Thus, we assert that the results of our study are robust and provide the most reliable evidence to date on the bidirectional associations and the adverse prognostic impact of comorbid COPD and depression or anxiety, which should inform clinical guidelines and practice. Finally, we join Dr Moullec and colleagues in calling for more research on effective interventions for patients with COPD with psychiatric comorbidities.

Acknowledgments

Other contributions: This research was performed at the University of Western Sydney.

Atlantis E, Fahey P, Cochrane B, Smith S. Bidirectional associations between clinically relevant depression or anxiety and COPD: a systematic review and meta-analysis. Chest. 2013:144(3):766-777.
 
Laurin C, Moullec G, Bacon SL, Lavoie KL. Impact of anxiety and depression on chronic obstructive pulmonary disease exacerbation risk. Am J Respir Crit Care Med. 2012;185(9):918-923. [CrossRef] [PubMed]
 
Centre for Reviews and Dissemination. CRD’s Guidance for Undertaking Reviews in Health Care. York, England: University of York; 2009.
 
Pouwer F, Atlantis E. Measuring and assessing depression in people with diabetes: implications for clinical practice.. In:Lloyd CE, Pouwer F, Hermanns N., eds. Screening for Depression and Other Psychological Problems in Diabetes: A Practical Guide. London, England: Springer; 2013:199-209.
 
Nicholson A, Kuper H, Hemingway H. Depression as an aetiologic and prognostic factor in coronary heart disease: a meta-analysis of 6362 events among 146 538 participants in 54 observational studies. Eur Heart J. 2006;27(23):2763-2774. [CrossRef] [PubMed]
 

Figures

Tables

References

Atlantis E, Fahey P, Cochrane B, Smith S. Bidirectional associations between clinically relevant depression or anxiety and COPD: a systematic review and meta-analysis. Chest. 2013:144(3):766-777.
 
Laurin C, Moullec G, Bacon SL, Lavoie KL. Impact of anxiety and depression on chronic obstructive pulmonary disease exacerbation risk. Am J Respir Crit Care Med. 2012;185(9):918-923. [CrossRef] [PubMed]
 
Centre for Reviews and Dissemination. CRD’s Guidance for Undertaking Reviews in Health Care. York, England: University of York; 2009.
 
Pouwer F, Atlantis E. Measuring and assessing depression in people with diabetes: implications for clinical practice.. In:Lloyd CE, Pouwer F, Hermanns N., eds. Screening for Depression and Other Psychological Problems in Diabetes: A Practical Guide. London, England: Springer; 2013:199-209.
 
Nicholson A, Kuper H, Hemingway H. Depression as an aetiologic and prognostic factor in coronary heart disease: a meta-analysis of 6362 events among 146 538 participants in 54 observational studies. Eur Heart J. 2006;27(23):2763-2774. [CrossRef] [PubMed]
 
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