results of the meta-analysis conformed to what would beexpected based on the work of Kraemer et al and similarwork by others (3,4). Meta-analysis is an important tech-nique that increasingly informs health care policy andclinical practice guidelines and recommendations. Re-searchers and clinicians need to be aware of the importantpitfalls that can lead to significant biases in reported re-sults. Hall et al would have done well by concluding thatthe literature on Tai Chi for chronic pain was not yet readyfor meta-analysis.

Ms Schieir has received funding from a Fonds de la Rechercheen Sante de Quebec (FRSQ) Bourse de Formation, FormationMaıtrise (2008–2010) and a Canadian Scleroderma ResearchGroup Studentship (Canadian Institutes of Health Research[CIHR] Strategic Training Initiative in Health Research grant,2002–2009). Dr. Thombs is supported by a New InvestigatorAward from the CIHR and an Etablissement de Jeunes ChercheursAward from the FRSQ.

Orit Schieir, MScAdemola Adeponle, MDMcGill UniversityMontreal, Quebec, CanadaKatherine Milette, BScJewish General HospitalMontreal, Quebec, CanadaBrett D. Thombs, PhDJewish General Hospital and McGill UniversityMontreal, Quebec, Canada

1. Hall A, Maher C, Latimer J, Ferreira M. The effectiveness of TaiChi for chronic musculoskeletal pain conditions: a systematicreview and meta-analysis. Arthritis Rheum 2009;61:717–24.

2. Kraemer HC, Gardner C, Brooks J III, Yesavage J. Advantages ofexcluding underpowered studies in meta-analysis: inclusionistversus exclusionist viewpoints. Psychol Methods 1998;3:23–31.

3. Ioannidis JP. Why most discovered true associations are in-flated. Epidemiology 2008;19:640–8.

4. Howard GS, Hill TL, Maxwell SE, Baptista TM, Farias MH,Coelho C, et al. What’s wrong with research literatures? Andhow to make them right. Rev Gen Psychol 2009;13:146–66.

DOI 10.1002/acr.20029

Reply

To the Editors:

The comments by Schieir and colleagues complicates anissue that is self evident: a pooled effect incorporates thebias from the individual trials. In our review we clearlyacknowledged that the individual trials provide poten-tially biased estimates of treatment effects. For example,the first sentence of our conclusion was, “The availabledata on the effect of Tai Chi are sparse and derived prin-cipally from low-quality studies.” That is why we are nowconducting our own trial to provide a more definitiveanswer (1).

We disagree with the authors’ suggestion of avoidingmeta-analysis as a solution to potential bias in trials.Avoiding meta-analysis does not solve the underlyingproblem because meta-analysis did not introduce the bias;it arose in the conduct and reporting of trials. There aremethods to assess the likely extent of publication bias in a

meta-analysis (e.g., funnel plot), but they require a reason-able number of trials and variation in sample size. Unfor-tunately, with only 7 trials these methods were not rele-vant in this review. We did however provide readers withinformation on the methodologic quality of each trial us-ing a validated scale (2–4).

Amanda Hall, MPE, BKINChris Maher, PhDJane Latimer, PhDThe George Institute for International Health

The University of SydneySydney, New South Wales, AustraliaManuela Ferreira, PhDThe University of SydneySydney, New South Wales, Australia

1. Hall A, Maher CG, Latimer J, Ferreira M, Lam P. A randomizedcontrolled trial of Tai Chi for long-term low back pain (TAICHI): study rationale, design, and methods. BMC Musculoske-let Disord 2009;10:55.

2. Maher C, Sherrington C, Herbert R, Moseley A, Elkins M.Reliability of the PEDro sale for rating quality of randomizedcontrolled trials. Phys Ther 2003;83:713–21.

3. De Morton N. The PEDro scale is a valid measure of the meth-odological quality of clinical trials: a demographic study. AustJ Physiother 2009;55:129–33.

4. Bhogal SK, Teasell RW, Foley NC, Speechley MR. The PEDroscale provides a more comprehensive measure of methodolog-ical quality than the Jadad scale in stroke rehabilitation litera-ture. J Clin Epidemiol 2005;58:668–73.

DOI 10.1002/acr.20030

Measures of psychological distress inpatients with arthritis: comment on thearticle by Fuller-Thomson and Shaked

To the Editors:

We read with great interest the recently published arti-cle in Arthritis Care & Research by Fuller-Thomson andShaked on factors associated with depression and suicidalideation among individuals with arthritis (1). Mentalhealth is an important component of health among pa-tients with chronic diseases such as arthritis (2), and weagree with the authors that knowledge of risk factors fordepression and improved screening and outreach for psy-chotherapeutic interventions can help improve the overallhealth of people with arthritis. The prevalence of seriouspsychological distress, frequent anxiety, and depressionhas been reported to be higher in adults with arthritis thanin those without arthritis (3). In the study by Fuller-Thompson and Shaked, 9.9% of persons with arthritisexperienced a major depressive episode in the preceding12 months, compared with 6.8% of persons without ar-thritis. However, items included in the mental health in-terview scale used in the study may have overestimatedthe difference in the prevalence of major depression be-tween those with and without arthritis.

Large population-based and community surveys oftenemploy abbreviated diagnostic interviews administered bylay interviewers. The Composite International DiagnosticInterview Short-Form (CIDI-SF), which screens for a major

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