Pediatr Blood Cancer 2014;61:954
LETTER TO THE EDITOR Antidepressant Use Among Survivors of Childhood, Adolescent, and Young Adult Cancer: Letter to the Editor Response
To the Editor: Although Kawada’s letter raised interesting points, we feel his concerns are unjustified and his choice of a comparable study inappropriate. His first concern is that he feels we have insufficient events per variable in our regression models for stratified analyses. We did not actually conduct stratified analyses in our study of antidepressant use among childhood cancer survivors [1]. We report 4,951 antidepressant prescriptions (events) with a total of four independent variable categories (cancer survivorship, urban/rural status, socioeconomic status, and attained age), composed of a total of 11 parameters in our primary multivariable regression model. For descriptive purposes, we divided antidepressants into categories and repeated the analysis with the same independent variables. Among six drug categories, five had a minimum of 692 events (prescriptions filled), which clearly meets the suggested 10–20 events per variable. We agree that there were a small number of events in the final category (monoamine oxidase inhibitors), and that this odds ratio, with its associated wide confidence interval, must be interpreted with caution. Similarly, Kawada was concerned that our number of events (n ¼ 515) in the survivor-only analysis is insufficient. In this analysis we had seven independent variable categories, composed of a total of 27 variables in the regression model. Again, this satisfies the minimum guideline of 10 events per variable. Kawada suggested that gender should be included in the logistic regression model for anti-depressant use among survivors and general population comparators. Since survivors and comparators were matched by gender, the addition of gender does not affect the estimate of risk of antidepressant use for survivors compared to the general population. In our survivor-only analysis we reported an increased likelihood of antidepressant use in female survivors (OR 2.02; 95% CI 1.63, 2.50). There was a similar increased risk for females in the general population (OR 1.88; 95% CI 1.76, 2.01). Both female and male survivors were more likely than comparators of the same sex to fill antidepressant prescriptions (ORfemale 1.23; 95% CI 1.07, 1.41; ORmale 1.19; 95% CI 1.01, 1.40). Kawada then compared our results to a study with a very different outcome; the risk of hospital contact for mental disorders among survivors [2]. Kawada focused on unipolar depression, however, antidepressants are prescribed for a much broader range of clinical indications. Finally, Kawada took issue with our lack of a clear relationship between age at childhood cancer diagnosis and risk of antidepressant use years later. Again, comparison is made with a study
evaluating a different outcome [2]. Lund et al. found that survivors diagnosed at younger ages had a higher risk of hospital contact for mental disorders than those diagnosed at older ages. Using hospital contact as an outcome will not capture survivors who are filling antidepressant prescriptions as outpatients, making comparisons difficult. We found that the likelihood of antidepressant drug use, adjusted for attained age, increased with increasing time from diagnosis (P-trend ¼ 0.026) in our universal health care system with stable access to care [3]. This novel finding highlights the ongoing needs of cancer survivors years after treatment and warrants further investigation. Rebecca J. Deyell, MD Division of Oncology Hematology and Bone Marrow Transplant British Columbia Children’s Hospital and University of British Columbia Vancouver, British Columbia, Canada Maria Lorenzi, MSc Cancer Control Research Program British Columbia Cancer Agency Vancouver, British Columbia, Canada John J. Spinelli, PhD Mary L. McBride, MSc Cancer Control Research Program British Columbia Cancer Agency Vancouver, British Columbia, Canada School of Population and Public Health University of British Columbia Vancouver, British Columbia, Canada
REFERENCES 1. Deyell RJ, Lorenzi M, Ma S, et al. Antidepressant use among survivors of childhood, adolescent and young adult cancer: A report of the Childhood, Adolescent and Young Adult Cancer Survivor (CAYACS) Research Program. Pediatr Blood Cancer 2013;60:816–822. 2. Lund LW, Winther JF, Dalton SO, et al. Hospital contact for mental disorders in survivors of childhood cancer and their siblings in Denmark: A population-based cohort study. Lancet Oncol 2013;14: 971–980. 3. McBride ML, Lorenzi MF, Page J, et al. Patterns of physician follow-up among young cancer survivors: Report of the Childhood, Adolescent, and Young Adult Cancer Survivors (CAYACS) research program. Can Fam Physician 2011;57:e482–e490.
Correspondence to: Rebecca J Deyell, Division of Pediatric Hematology/Oncology/BMT, British Columbia Children’s Hospital, Room A119C, 4480 Oak Street, Vancouver, British Columbia, Canada. E-mail: [email protected]
Received 7 October 2013; Accepted 4 November 2013 C
2013 Wiley Periodicals, Inc. DOI 10.1002/pbc.24885 Published online 19 December 2013 in Wiley Online Library (wileyonlinelibrary.com).
LETTER TO THE EDITOR Antidepressant Use Among Survivors of Childhood, Adolescent, and Young Adult Cancer: Letter to the Editor Response
To the Editor: Although Kawada’s letter raised interesting points, we feel his concerns are unjustified and his choice of a comparable study inappropriate. His first concern is that he feels we have insufficient events per variable in our regression models for stratified analyses. We did not actually conduct stratified analyses in our study of antidepressant use among childhood cancer survivors [1]. We report 4,951 antidepressant prescriptions (events) with a total of four independent variable categories (cancer survivorship, urban/rural status, socioeconomic status, and attained age), composed of a total of 11 parameters in our primary multivariable regression model. For descriptive purposes, we divided antidepressants into categories and repeated the analysis with the same independent variables. Among six drug categories, five had a minimum of 692 events (prescriptions filled), which clearly meets the suggested 10–20 events per variable. We agree that there were a small number of events in the final category (monoamine oxidase inhibitors), and that this odds ratio, with its associated wide confidence interval, must be interpreted with caution. Similarly, Kawada was concerned that our number of events (n ¼ 515) in the survivor-only analysis is insufficient. In this analysis we had seven independent variable categories, composed of a total of 27 variables in the regression model. Again, this satisfies the minimum guideline of 10 events per variable. Kawada suggested that gender should be included in the logistic regression model for anti-depressant use among survivors and general population comparators. Since survivors and comparators were matched by gender, the addition of gender does not affect the estimate of risk of antidepressant use for survivors compared to the general population. In our survivor-only analysis we reported an increased likelihood of antidepressant use in female survivors (OR 2.02; 95% CI 1.63, 2.50). There was a similar increased risk for females in the general population (OR 1.88; 95% CI 1.76, 2.01). Both female and male survivors were more likely than comparators of the same sex to fill antidepressant prescriptions (ORfemale 1.23; 95% CI 1.07, 1.41; ORmale 1.19; 95% CI 1.01, 1.40). Kawada then compared our results to a study with a very different outcome; the risk of hospital contact for mental disorders among survivors [2]. Kawada focused on unipolar depression, however, antidepressants are prescribed for a much broader range of clinical indications. Finally, Kawada took issue with our lack of a clear relationship between age at childhood cancer diagnosis and risk of antidepressant use years later. Again, comparison is made with a study
evaluating a different outcome [2]. Lund et al. found that survivors diagnosed at younger ages had a higher risk of hospital contact for mental disorders than those diagnosed at older ages. Using hospital contact as an outcome will not capture survivors who are filling antidepressant prescriptions as outpatients, making comparisons difficult. We found that the likelihood of antidepressant drug use, adjusted for attained age, increased with increasing time from diagnosis (P-trend ¼ 0.026) in our universal health care system with stable access to care [3]. This novel finding highlights the ongoing needs of cancer survivors years after treatment and warrants further investigation. Rebecca J. Deyell, MD Division of Oncology Hematology and Bone Marrow Transplant British Columbia Children’s Hospital and University of British Columbia Vancouver, British Columbia, Canada Maria Lorenzi, MSc Cancer Control Research Program British Columbia Cancer Agency Vancouver, British Columbia, Canada John J. Spinelli, PhD Mary L. McBride, MSc Cancer Control Research Program British Columbia Cancer Agency Vancouver, British Columbia, Canada School of Population and Public Health University of British Columbia Vancouver, British Columbia, Canada
REFERENCES 1. Deyell RJ, Lorenzi M, Ma S, et al. Antidepressant use among survivors of childhood, adolescent and young adult cancer: A report of the Childhood, Adolescent and Young Adult Cancer Survivor (CAYACS) Research Program. Pediatr Blood Cancer 2013;60:816–822. 2. Lund LW, Winther JF, Dalton SO, et al. Hospital contact for mental disorders in survivors of childhood cancer and their siblings in Denmark: A population-based cohort study. Lancet Oncol 2013;14: 971–980. 3. McBride ML, Lorenzi MF, Page J, et al. Patterns of physician follow-up among young cancer survivors: Report of the Childhood, Adolescent, and Young Adult Cancer Survivors (CAYACS) research program. Can Fam Physician 2011;57:e482–e490.
Correspondence to: Rebecca J Deyell, Division of Pediatric Hematology/Oncology/BMT, British Columbia Children’s Hospital, Room A119C, 4480 Oak Street, Vancouver, British Columbia, Canada. E-mail: [email protected]
Received 7 October 2013; Accepted 4 November 2013 C
2013 Wiley Periodicals, Inc. DOI 10.1002/pbc.24885 Published online 19 December 2013 in Wiley Online Library (wileyonlinelibrary.com).
