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Cost-effectiveness of a primary care depression intervention |
Pyne J M, Rost K M, Zhang M, Williams D K, Smith J, Fortney J |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The study examined a quality improvement intervention (enhanced care) for depression in primary care settings relative to usual care. The intervention was to train the primary care team to assess, educate and monitor depressed patients during the acute and continuation stage of their depression treatment episode over 1 year.
Study population The study population comprised a group of primary care patients beginning a new treatment episode for major depression, as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). Patients were eligible for this analysis if they:
had reported 5 or more of the 9 criteria for major depression in the past 2 weeks using the Inventory to Diagnose Depression;
had screened negative for lifetime mania;
had screened negative for lifetime alcohol dependence with current drinking;
did not meet the DSM-IV criteria for bereavement-related depression;
had reported no antidepressant medication in the last month and specialty mental health care in the last 6 months; and
had sufficient SF-36 data at baseline, and 6 and 12 months to calculate the SF-36 quality-adjusted index scores.
Setting The setting was primary care. The economic study was carried out in the USA.
Dates to which data relate Both the effectiveness data and resource use data were taken from a study published in 2000. The price year was 2000.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was carried out prospectively on the same sample of patients as that used in the effectiveness analysis.
Study sample The authors did not report that power calculations were carried out to estimate the impact of chance on the results. There were 653 potential eligible patients, of whom 174 (26.6%) refused to participate. Among the remaining 479 eligible patients, 115 patients who had not been recently treated underwent the intervention in the 6 clinics randomised to enhanced care and 96 received no intervention in the 6 clinics randomised to usual care.
Study design The study was a multi-centred, randomised controlled trial. The authors explicitly reported that a 2-stage stratification plan was used to randomly assign 6 practices to the enhanced care group and 6 to the usual care group. The patients were followed up for 1 year. The loss to follow-up was reported. In all but three cases, the interviewer was blinded to the patient's treatment condition.
Analysis of effectiveness The analysis of effectiveness appears to have been conducted on an intention to treat basis. The primary health outcome used was the quality-adjusted life-years (QALYs). The commonly used health-related quality of life instrument, the SF-36, was used to evaluate quality of life. The authors reported that, with three exceptions, the patients in the two groups were comparable at baseline in terms of sociodemographic and clinical characteristics.
Effectiveness results The effect of the intervention on QALYs, controlling for the sociodemographic and clinical covariates, was significant (beta=0.04, p<0.05).
Using the bootstrap with replacement sample method, the mean incremental outcome effect of the intervention relative to usual care was 0.041 QALYs (95% confidence interval, CI: 0.040 - 0.042).
The decrease in depression severity from baseline to 12 months was 7.7 units greater in the enhanced group than in the usual care group, (p<0.05).
The intervention improved the probability of depression remission and role functioning over time.
Clinical conclusions The quality improvement depression intervention was more effective than usual care.
Measure of benefits used in the economic analysis The measure of health benefits used was the QALYs. These were the same estimates as those used in the effectiveness analysis.
Direct costs The direct costs of the clinics included the training and implementation costs for physicians, nurses and office staff coordinators for the acute phase of the intervention. The training costs covered primary trainee time, airfare, meals and lodging, the training manual, and trainer time. The implementation costs covered primary care clinic staff time for patient screening, preparation for and delivery of the patient intervention, post session recordkeeping, communication among providers delivering the intervention, and post training supervision. The direct costs of the patients included outpatient health care expenditure, time, and transportation. Hospital costs were not included. Outpatient health care expenditures for emergency room visits, primary care and specialty mental health care visits, and psychotropic medication during the time of intervention were estimated from patient reports at the 6- and 12-month interviews. Preintervention health care expenditure was estimated for the 6 months prior to the baseline interview.
The costs were estimated in 1999 and 2000. All the costs were adjusted to reflect year 2000 dollars. The price year was 2000. Discounting was not carried out, which was appropriate as the costs were incurred during one year.
Statistical analysis of costs The costs were not treated stochastically. No statistical tests were carried out in the cost analysis.
Indirect Costs The indirect costs were not included.
Sensitivity analysis Four one-way sensitivity analyses were carried out to investigate variability in the data and the comparability of the results.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The effect of the intervention on the costs, controlling for the sociodemographic and clinical covariates, was statistically significant (beta=0.40, p=0.006).
Using the bootstrap with replacement sample method, the mean incremental cost effect of the intervention relative to usual care was $634 (95% CI: 618 - 650).
Synthesis of costs and benefits The costs and benefits were combined by calculating an incremental cost-effectiveness ratio. The mean incremental cost-effectiveness ratio for the intervention versus usual care was $15,463 per QALY. In the sensitivity analyses, the cost-effectiveness ratios ranged from $11,341 to $19,976 per QALY.
Authors' conclusions The mean incremental cost-effectiveness for this primary care depression intervention was very cost-effective relative to commonly delivered primary care interventions and commonly used cost-effectiveness ratio thresholds.
CRD COMMENTARY - Selection of comparators The comparator used was justified on the grounds that it represented current practice.
Validity of estimate of measure of effectiveness The basis of the analysis was a randomised controlled trial, which was appropriate for the study question. The patient groups were shown to be comparable at the baseline analysis. The analysis of effectiveness was handled credibly, and appropriate statistical analyses were conducted to test for significant differences.
Validity of estimate of measure of benefit The QALYs were estimated using utility values obtained from patients from community primary care practices using the commonly used SF-36 instrument. Both the advantages and limitations of this approach in terms of generalisability were addressed.
Validity of estimate of costs Although the authors stated clearly that a societal perspective was adopted, not all of the possible costs were included. For example, the study did not include the indirect costs, or the costs for diagnostic testing, nonpsychotropic medications, and inpatient services. The authors reported that the skewed cost distribution may, potentially, have reduced their ability to draw definitive conclusions about how the intervention affected the costs.
Other issues The authors made broad comparisons of their findings with those from other studies. They also addressed the issue of generalisability to other settings. The authors do not appear to have presented their results selectively and their conclusions reflected the scope of the analysis. The authors reported that the accuracy of the results might have been affected by missing data.
Implications of the study The authors recommended that this intervention be implemented for depressed primary care patients beginning a new treatment episode.
Source of funding Supported by a VA Research Career Development Award and the Veterans Integrated Services Network 16 Mental Illness Research, Education and Clinical Center (grants MH54444, MH63651 and AA12085).
Bibliographic details Pyne J M, Rost K M, Zhang M, Williams D K, Smith J, Fortney J. Cost-effectiveness of a primary care depression intervention. Journal of General Internal Medicine 2003; 18(6): 432-441 Other publications of related interest Rost K, Nutting P, Smith J, Werner J. Designing and implementing a primary care intervention trial to improve the quality and outcome of care for major depression. General Hospital Psychiatry 2000;22:66-77.
Schoenbaum M, Unutzer J, Serbourne C, et al. Cost-effectiveness of practice-initiated quality improvement for depression: results of a randomised controlled trial. JAMA 2001;286:1325-30.
Katon W, Robinson P, Von Korff M, et al. A multifaceted intervention to improve treatment of depression in primary care. Archives of General Psychiatry 1996;53:924-32.
Rost K, Nutting P, Smith JL, Elliot CE, Dickinson M. Managing depression as a chronic disease: a randomised trial of ongoing treatment in primary care. BMJ 2002;325:934-40.
Rost K, Nutting P, Smith JL, Werner J, Duan N. Improving depression outcomes in community primary care practice: a randomised trial of the QuEST intervention. Journal of General Internal Medicine 2001;16:143-9.
Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Depression /economics /therapy; Depressive Disorder /economics /prevention & Female; Health Care Costs; Health Services Research; Humans; Male; Primary Health Care /economics /standards; Quality Assurance, Health Care; Quality-Adjusted Life Years; United States; control AccessionNumber 22003000988 Date bibliographic record published 30/06/2005 Date abstract record published 30/06/2005 |
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