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Cost-effectiveness of treatments for major depression in primary care practice |
Lave J R, Frank R G, Schulberg H C, Kamlet M S |
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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 Pharmacotherapy, interpersonal psychotherapy within a standardised framework, and primary physician's usual care in the treatment of major depression.
Economic study type Cost-effectiveness analysis and cost-utility analysis.
Study population Study subjects met DSM-III-R criteria for current major depression.
Setting The practice setting was primary care. The economic study was carried out in Pittsburg, USA.
Dates to which data relate The period during which the effectiveness analysis and costings were carried out was unclear. The price year was not stated.
Source of effectiveness data The estimates for the effectiveness of treatments for major depression were derived from a single study although information from a previous clinical trial was utilised to develop the depression-free days (DFDs) indicator.
Link between effectiveness and cost data Prospective costing was undertaken on the effectiveness study sample.
Study sample Primary care patients suffering from major depression were assigned to one of three treatment arms: pharmacotherapy (n=91), interpersonal psychotherapy (n=93), and primary physician's usual care (n=92). The three groups were shown to be comparable in terms of baseline characteristics (age, sex, ethnicity, marital status, education, employment status, and clinical health status). No power calculations were reported. No exclusions were reported.
Study design This was a randomised controlled trial. It is not clear if the study was single or multi-centred. The duration of follow-up was 12 months. No losses to follow-up were recorded.
Analysis of effectiveness The analysis of the clinical study was undertaken on an intention-to-treat basis. The primary health outcomes used in the analysis were Hamilton Rating Scale-Depression (HRS-D) and Beck Depression Inventory (BDI). These two outcomes were used to compute a third outcome, that of Depression-free Days (DFDs).
Effectiveness results Over the 12-month period, NT patients experienced 243 DFDs, IPT patients experienced 234 DFDs and UC patients experienced 185 DFDs, when assessed with HRS-D.
When assessed with the BDI scores the numbers of DFDs were 220 for NT patients, 187 for IPT patients and 148 for UC patients.
The differences across groups were statistically significant (p<0.01).
Clinical conclusions Standardised depression treatments lead to better outcomes compared to usual care.
Measure of benefits used in the economic analysis The benefit measure was quality-adjusted life years (QALYs) derived from DFDs, using utility weights assigned to depression based on previous research. (The transformation assumed that a non depressed person has a utility of 1 whilst a person meeting the criteria for having major depression scored 0.59.) Utilities were based on an average of 6 sources reported in the literature.
Direct costs Direct costs included medical services costs (source: 1995 Medicare payment rates) as well as costs incurred in administering standardised treatments (source: Redbook, 1995). Administrative costs were estimated. Resources were listed separately from the costs. Discounting was not relevant due to the short period of follow-up.
Statistical analysis of costs Chi-squared or ANOVA tests were used to determine whether costs varied across the three treatment groups (p=0.05).
Indirect Costs Indirect costs included transportation (estimates) and time costs (estimates) incurred in obtaining services. Discounting was not applied due to the short period of follow-up.
Sensitivity analysis Sensitivity analyses were performed using models to assess the impact on the cost-effectiveness ratios of variability in the data. First the results were determined from two different depression scales, second the utility difference was reduced by 0.01, third it was assumed that IPT could be performed by non psychiatric mental health personnel which reduced the cost of delivering the IPT protocol by 20%.
Estimated benefits used in the economic analysis The benefits results were not reported separately but are included in the synthesis of costs and benefits, as shown below.
Cost results Total average intervention costs (direct plus indirect costs) were:
interpersonal psychotherapy, $1,764.80,
Nortriptyline hydrochloride, $1,506,
usual care, $675.70.
Direct costs alone were:
interpersonal psychotherapy, $1,398.60,
Nortriptyline hydrochloride, $1,291.40,
usual care, $553.20.
Synthesis of costs and benefits When comparing NT versus UC cost-effectiveness ratios, $13.14 in direct costs are incurred for each additional DFD experienced by NT patients ($11,695 per QALY assuming that the difference between a depressed day and a DFD is 0.41 of a quality-adjusted day, and to $15,202 per QALY assuming that the difference between a depressed day and a DFD is 0.31 of a quality-adjusted day). Cost-effectiveness ratios increased when full costs were incurred, and varied depending on the depression assessment instrument used. When comparing IPT versus UC the cost-effectiveness ratio falls if non-psychiatric personnel at 80% of the psychiatrists' cost per session deliver IPT equally effectively. Deriving outcomes from HRS-D scores, the direct cost per IPT-achieved DFD falls ($22.82 to $17.56), as does the cost per QALY (from $20,310 to $15,358). IPT versus UC cost-effectiveness ratios always exceeded those for NT versus UC.
Authors' conclusions The authors conclude that standardised treatments for depression lead to better outcomes than usual care but also lead to higher costs. However, estimates derived within the study for costs per QALY gained for standardised pharmacotherapy are comparable with those found for other routine treatments in practice.
CRD COMMENTARY - Selection of comparators The selection of pharmacotherapy, interpersonal psychotherapy within a standardised framework and the comparator of primary physician's usual care in the treatment of major depression were justified within the study.
Validity of estimate of measure of benefit The estimates for cost-effectiveness ratios are likely to be internally valid, though the authors point to a number of potential biases (although they are not able to fully determine the direction of bias). These include the use of specially trained physicians for NT (different from the regular physicians), the lack of blinding for patients and physicians, and the short period of follow-up). Additionally the treatment of QALY computations was justified given their derivation from utility estimated from the literature and the assessment of DFDs using two instruments.
Validity of estimate of costs Adequate costing details were provided although no overall price year was stated. Indirect costs were calculated and also computed as part of the cost-effectiveness ratio estimates.
Other issues Sensitivity analyses were performed to account for potential variability of the results using what appear to be reasonable assumptions. Statistical analyses were comprehensive around both outcomes and costs. The authors state that this was the first cost-effectiveness analysis in this area and therefore comparisons with other studies were not possible.
Implications of the study Standardised treatments for depression, based on these results, lead to better outcomes than usual care but also lead to higher costs. Incremental Cost-per-QALY values for standardised pharmacotherapy are comparable with other programmes of routine care.
Source of funding Funded by grants MH47544 to the Graduate School of Public Health (Dr Lave) and MH45851 to the Department of Psychiatry (Dr Schulberg) at the University of Pittsburgh, Pittsburgh, Pa, from the National Institute of Mental Health, Bethesda, MD, USA.
Bibliographic details Lave J R, Frank R G, Schulberg H C, Kamlet M S. Cost-effectiveness of treatments for major depression in primary care practice. Archives of General Psychiatry 1998; 55(7): 645-651 Indexing Status Subject indexing assigned by NLM MeSH Adult; Combined Modality Therapy; Cost-Benefit Analysis; Depressive Disorder /drug therapy /economics /therapy; Female; Health Care Costs; Health Services /utilization; Humans; Male; Middle Aged; Nortriptyline /economics /therapeutic use; Primary Health Care /economics; Psychiatric Status Rating Scales; Psychotherapy /economics; Quality-Adjusted Life Years; Severity of Illness Index; Treatment Outcome AccessionNumber 21998001072 Date bibliographic record published 30/09/2000 Date abstract record published 30/09/2000 |
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