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Economic assessment of a six-year project with extensive use of dental hygienists in the dental care of children: a pilot study |
Hannerz H, Westerberg I |
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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 Extensive use of dental hygienists with reduced input of dentists in the delivery of dental health care. A test dental clinic using an alternative division of labour was compared to a conventional dental clinic.
Type of intervention Primary prevention and treatment.
Economic study type Cost-effectiveness analysis.
Study population Patients born in 1975 who attended the dental clinic.
Setting Dental clinic. The economicstudy was carried out in Gustafs, Sweden.
Dates to which data relate Resource data and data in the effectiveness analysis were collected during 1988-1993, for the intervention, and the second half of 1993, for the comparator. 1993 prices were used in the final report.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data No adequate details of the costing procedure were provided. The costing was undertaken retrospectively.
Study sample No power calculations were reported. 39 patients were included in the intervention group and 41 in the comparator. The intervention group and the control group were treated in different public dental clinics. Two dentists participated in the study as referees of diagnostic decisions. The overall percentage of original study sample patients (n=132) excluded was 39. The percentage of patients excluded from the initial study sample for the intervention was 0.0%. For the comparator 56% of original sample patients were excluded. In the test clinic, dentist, dental hygienist, and dental prophylaxis assistant services were used at a rate of 0.45, 1.61, and 0 hours per average registered patient 3-19 years of age per year (hours/pat./yr.). The corresponding values for the control clinic were 0.70, 0.25, and 0.34 hours/pat./yr., respectively.
Study design This was a pilot study in the form of a non-randomised trial with concurrent controls. The studywas a multicentre study in 2 centres, ('test clinic' and 'control clinic'). The duration of follow-up for the patients in the test clinic was 6 years. No loss to follow-up was reported.
Analysis of effectiveness It was not clear whether the study was based on intention to treat or on treatment completers only. The primary health outcome used was mean caries development (incidence). In order to measure the incidence, two outcome measures, based on different levels of tooth decay, were used: DFS and DFS+D2S. A logistic regression analysis was carried out to discover the main explanatory variables affecting the mean caries development (incidence). The analysis controlled for patients' socioeconomic background, gender and prevalence of caries (measured by DFS) at 13 years of age.
Effectiveness results The mean incidences (standard deviation) under the DFS measure were 1.13 (SD, 1.42) with 51% of zero values, in the intervention, and 3.29 (2.99) with 20% of zero values, in the comparator (t-value, -4.1; p<0.001). The same outcome measure using the DFS+D2S was 1.77 (2.18), with 41% of zero values for the test group, and 4.15 (3.43) with 17% of zero values for the control group (t-value, -3.7; P<0.001). The regression analysis revealed the statistically significant explanatory values for the variables "clinic" and "caries prevalence at 13 years of age" (both had a p value <0.001).
Clinical conclusions The finding of a qualitatively identical result under two different outcome measures was considered, by the authors, to support the internal validity of the study. The authors concluded that "the results can thus be explained by the difference in input of clinical measures as consequence of the differences in educational and legal competence, i.e. a more extensive practice of preventive care at the test clinic".
Measure of benefits used in the economic analysis The outcome measure used was caries avoided. The results were reported in terms of mean caries incidence during a five-year period (first observation was used as the 'prevalence of caries at 13 years of age'). Approximal caries was registered according to criteria from a previously published study (Koch, 1967). Two measures were used for 'incidence of caries', each representing a different degree of severity of caries: DFS and DFS + D2S.
Direct costs Costs were discounted. The quantities of resources used were broadly reported separately from the costs. The costs measured were operating costs. While no adequate details of cost components and their values were reported, the authors reported that "all variable costs were included". The perspective adopted in the cost analysis was not explicitly specified. The unit costs were calculated from the "yearly financial accounts". The quantities of resources used were collected from 1988 to 1993. The prices used were deflated to 1993 and discounted to 1988. The cost items reported as excluded were "fixed" costs and overhead costs.
Sensitivity analysis A one-way simple sensitivity analysis was carried out using the discount rate (10% instead of 6%).
Estimated benefits used in the economic analysis The mean incidences (standard deviation) under the DFS measure were 1.13 (SD, 1.42) with 51% of zero values, in the intervention, and 3.29 (2.99) with 20% of zero values, in the comparator (t-value, -4.1; P<0.001). The same outcome measure using the DFS+D2S was 1.77 (2.18), with 41% of zero values for the test group, and 4.15 (3.43) with 17% of zero values for the control group (t-value, -3.7; P<0.001).
Cost results The incremental cost per individual for the intervention with respect to the comparator turned out to be SEK177 (SEK546 incremental cost saving - SEK369 incremental cost) per patient at a 6% discount rate. The costs were calculated for a period of 6 years
Synthesis of costs and benefits The costs and benefits were not combined since the intervention was shown to be the dominant strategy. The sensitivity analysis yielded a "positive, but somewhat smaller net benefit (cost saving with respect to the comparator)".
Authors' conclusions The authors concluded that: "The results indicate that the implementation of an alternative division of labour in accordance with the tested model (intervention) might be profitable. The results of the study encourage the setting up of a more comprehensive investigation, including a larger number of patients and more than one control clinic".
CRD COMMENTARY - Selection of comparators The reason for the choice of comparator is clear. You, as a database user, should consider whether it is a widely used health technology in your own setting.
Validity of estimate of measure of benefit The internal validity of the estimate of benefit measure may be weakened by the lack of randomisation. The duration of the study was thought to represent an important shortcoming since "the benefit would be likely to become even greater when calculated for a time span of more than six years". Also, the small number of patients involved was recognised as an element affecting the reliability of the results, so that the authors considered the study to be a pilot study.
Validity of estimate of costs Resource quantities were broadly reported separately from prices. No adequate details of cost estimation were reported and "fixed" (capital) and overhead costs were excluded from the analysis. The study lacked a comprehensive and detailed cost analysis.
Other issues The authors considered their study to be a cost-benefit analysis, although the reported benefits were only costs saved (therefore, the study should be categorised as a cost-effectiveness rather than a cost-benefit analysis). In view of the lack of randomisation, a comprehensive sensitivity analysis, and a sound cost analysis, the results need to be treated with some caution. The issue of generalisability to other settings or countries was not addressed.
Bibliographic details Hannerz H, Westerberg I. Economic assessment of a six-year project with extensive use of dental hygienists in the dental care of children: a pilot study. Community Dental Health 1996; 13(1): 40-43 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Child; Cost-Benefit Analysis; DMF Index; Dental Care for Children /economics; Dental Caries /economics /prevention & Dental Clinics /economics; Dental Hygienists /economics; Female; Humans; Incidence; Longitudinal Studies; Male; Outcome Assessment (Health Care); Pilot Projects; Prevalence; Regression Analysis; Sweden; control AccessionNumber 21996001645 Date bibliographic record published 31/07/1999 Date abstract record published 31/07/1999 |
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