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Economic analysis of a pragmatic randomised trial of home visits by a nurse to elderly people with hypertension in Mexico |
Garcia-Pena C, Thorogood M, Wonderling D, Reyes-Frausto 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 The use of home visits made by trained nurses, at least fortnightly, in the care of elderly people with hypertension. The nurses measured blood pressure, informed the patients and discussed possible lifestyle changes with them. Independent of this type of care, the patients also received the usual care provided by their family physicians.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised hypertensive patients (systolic/diastolic blood pressure of at least 160/90 mmHg) who were aged 60 years or older.
Setting The setting was community care. The study was performed in Mexico.
Dates to which data relate The effectiveness and resource use data were collected between August 1998 and April 1999. The price year was 1998.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was performed prospectively on the same sample population as that used in the effectiveness analysis.
Study sample Sample size calculations, to assure a certain power, do not appear to have been performed in the planning phase of the study. Among 4,777 individuals aged 60 years or older, those who were known to have hypertension or who were newly diagnosed with hypertension were considered for inclusion in the effectiveness analysis. A total of 911 patients were eligible for the study. Before randomisation, 8 patients died, 101 moved away and 64 refused to participate in the study. The final study sample comprised 718 patients. Of these, 364 patients were randomly assigned to the intervention group and 354 to the control group. The authors did not report that the study sample was representative of the study population.
Study design This was a randomised controlled study. The authors did not report if the patients were recruited from multiple centres, but this may have been the case given the large sample size. The method of randomisation was not reported. The duration of follow-up was 6 months. Nineteen patients in the intervention group and 16 in the control group dropped out before the final evaluation. The authors reported that a different team of nurses measured the blood pressure and weighed participants at baseline and final follow-up. This appears to have represented the blinding method used for the outcome assessment.
Analysis of effectiveness The basis for the effectiveness analysis was not reported, although it appears to have been treatment completers only. The primary health outcomes assessed were:
the mean reduction in systolic and diastolic blood pressure when the intervention and control groups were compared;
the percentage increase in participants that reported taking a brisk walk 6 months after the intervention; and
the proportion of patients that did not receive antihypertensive medication at baseline and at the final assessment.
The intervention and control groups appeared similar for numerous factors. For example, their mean age, gender, education level, income, lifestyle risk factors (e.g. current smokers), clinical risk factors (e.g. diabetes mellitus, angina pectoris, acute myocardial infarction, known hypertension), mean weight, body mass index, sodium excretion, exercise (not walking regularly, walking briskly), mean blood pressure, and baseline blood pressure. The data about the presence of risk factors, use of medication and self-reported level of physical activity were collected through a questionnaire completed by the patients.
Effectiveness results Six months after the intervention had been implemented, when comparing the intervention and control groups, the mean reduction in systolic blood pressure was 3.31 mmHg (95% confidence interval, CI: 0.29 - 6.32), (p=0.03) and the mean reduction in diastolic blood pressure was 3.67 mmHg (95% CI: 2.12 - 5.22), (p<0.001).
The increase in patients that reported taking a brisk walk 6 months after the intervention was 12.9% in the intervention group and 5.2% in the control group, (p=0.0004).
The proportion of patients that did not receive antihypertensive medication decreased between the baseline and the final assessment, from 28.4 to 15.9% in the intervention group, and from 32.2 to 26.9% in the control group, (p=0.001).
Clinical conclusions It appears that home visits made by nurses have helped patients to control their hypertension. Both the systolic and diastolic blood pressure decreased significantly for patients in the intervention group in comparison with the control group. Also, at the same time, a higher percentage of patients in the intervention group reported taking brisk walks and a significantly lower percentage required antihypertensive medication.
Measure of benefits used in the economic analysis The measure of benefit used in the economic analysis was a reduction of 1 mmHg in the systolic and diastolic blood pressure.
Direct costs Most, but not all, of the resource quantities were reported separately from the costs. The direct costs considered in the economic analysis were those of the health service. These were for training the nurses, equipment, home visits and travel. The training costs included training from a cardiologist, geriatrician, physical therapist, psychiatrist, supervisor and researcher, the clinic space used for the course, and the time spent for the nurses to attend the course. The equipment costs included sphygmomanometers, stethoscopes, uniforms, supplies and stationery. The direct costs were obtained from the clinical trial, institutional records, the institutional distributor of the equipment, and the Mexican Institute of Social Security. Therefore, the costs were estimated from actual data. Discounting was not performed but, as the authors stated, it was irrelevant since the period considered at analysis was 6 months. The authors stated that only the costs of the sphygmomanometers were discounted (6% rate) due to the capital life expectancy of this equipment.
Only the costs of the intervention were considered and reported in the economic analysis, as the authors showed that the number of physician visits was not significantly different between the two groups. Therefore, the costs reported in the economic analysis were the total incremental cost of implementing the intervention, and the incremental costs per patient of receiving home visits by nurses in addition to the care provided by physicians. The price year was 1998.
Statistical analysis of costs For the mean costs, some CIs were estimated, while for some resource quantities, the mean and standard deviation were reported. For comparisons, t-tests appear to have been used. In addition, the CIs for the cost-effectiveness ratios were estimated using Fieller's method.
Indirect Costs At the beginning of the study, the authors planned to collect data to assess the indirect costs associated with patient or family time lost. However, none of the participants reported a cost value for the time spent during the visits. The authors therefore decided to exclude these costs.
Currency Mexican pesos and US dollars ($). The exchange rate was $1 = 9.15 pesos.
Sensitivity analysis No sensitivity analyses were performed.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' and the 'Synthesis of Costs and Benefits' sections.
Cost results The total cost of home visits made by nurses was 59,096.82 pesos ($6,180,99).
The average intervention cost per patient was 34.61 pesos (95% CI: 34.44 - 35.46; $3.78), (p=0.000).
The costs associated with the care provided by physicians was assumed to be zero for both the intervention and control groups, as there were no statistically significant differences between them in terms of the number of visits, (p=0.22).
Synthesis of costs and benefits The estimated benefits and costs were combined by calculating incremental cost-effectiveness ratios (ICERs). These measured the cost/mmHg reduction in systolic and diastolic blood pressure when home visits made by nurses were performed in addition to physician care to elderly hypertensive patients.
The ICERs were 10.46 pesos (95% CI: 5.51 - 129.31) or $1.14 (95% CI: 0.60 - 14.13) per mmHg reduction in systolic blood pressure, and 9.43 pesos (95% CI: 2.49 - 19.90) or $1.03 (95% CI: 0.27 - 2.17) per mmHg reduction in diastolic blood pressure.
Authors' conclusions Home visits made by nurses may represent a cost-effective intervention for reducing blood pressure among elderly Mexican hypertensive patients.
CRD COMMENTARY - Selection of comparators A justification was given for the comparator chosen. The treatment of elderly hypertensive patients by their family physicians (without home visits by the nurses) was the current practice in the authors' setting. However, the authors did not state what this type of care consisted of. You should consider which is the type of care most commonly used for elderly hypertensive patients in your own setting.
Validity of estimate of measure of effectiveness A randomised controlled study was undertaken, which seems to have been appropriate for the study question. The randomisation method used to allocate the patients to the study groups was not reported. Therefore, it is not possible to assess objectively whether this was appropriate. The outcome assessment appears to have been blinded since a different team of nurses carried it out. Although the authors did not report any evidence that the study sample was representative of the study population, it is likely that it was representative since the sample size was large and the patients were probably selected from several centres. The patient groups were shown to be similar at analysis.
The basis for the effectiveness analysis appears to have been treatment completers only, which would be associated with a risk of bias on account of patient withdrawals. However, the numbers of patients that withdrew before the final examination were very similar for both the intervention and control groups. The fact that the patients also received the care provided by physicians introduces uncertainty into the reliability of the conclusions. This is because the type and quality of physician care may have differed according to the group to which the patients belonged, although the number of physician visits was not significantly different between the two groups. Therefore, the results obtained may not have been directly and solely related to the intervention considered at analysis, but also to other differences associated with the physician care received by the patients. The authors reported an additional limitation in that no information about the sustainability of the intervention over a longer period of time than that considered in the present study was available.
Validity of estimate of measure of benefit The estimation of benefits was obtained directly from the effectiveness analysis and is an intermediate outcome. This choice of estimate was not justified. The authors remarked that some other measures of health benefit, such as mortality, morbidity or quality of life, could be considered.
Validity of estimate of costs The authors reported that, in the first instance, they considered a health service and a patient perspective. Ultimately, they only considered the former (health service) since they were unable to estimate the indirect costs. The authors reported that the costs relating to research were excluded, which seems appropriate given that only the costs associated with implementing the intervention should be considered. The costs relating to the physician care provided to both the intervention and control groups were not included since the groups were shown to be not significantly different in terms of the number of visits. The costs of hypertension medication were also not reported, but they may have been relevant. Some, but not all, of the resource quantities were reported separately from the costs. The price year was reported. Statistical analyses were performed, not only for the costs but also for some resource quantities and for the estimated ICERs. The Fieller's method, which is accepted as one of the most appropriate methods for estimating CIs for ICERs, was used to estimate CIs for the cost-effectiveness ratios. Discounting was not performed, which was appropriate as the period of analysis was shorter than 2 years.
Other issues The authors did not make appropriate comparisons of their findings with those from other studies. They justified this on the grounds of the lack of available information for similar interventions performed in Mexico. The issue of the generalisability of the results was not addressed. The authors' conclusions appropriately reflected the scope of the analysis.
Implications of the study The authors recommended that further research be performed so that the results of this study may be compared with those from other interventions aimed at blood pressure reduction among the elderly hypertensive population in Mexico.
Source of funding Funded by the National Council of Science and Technology, Mexico and the Mexican Institute of Social Security.
Bibliographic details Garcia-Pena C, Thorogood M, Wonderling D, Reyes-Frausto S. Economic analysis of a pragmatic randomised trial of home visits by a nurse to elderly people with hypertension in Mexico. Salud Publica de Mexico 2002; 44(1): 14-20 Other publications of related interest Garcia-Pena C, Thorogood M, Armstrong B, Reyes- Frausto S, Munoz O. Pragmatic randomised trial of home visits by a nurse to elderly people with hypertension in Mexico. International Journal of Epidemiology 2001;30(6):1485-91.
Garcia-Peza C, Thorogood M, Reyes S, Salmeron-Castro J, Duran C. The prevalence and treatment of hypertension in elderly population. Salud Publica de Mexico 2001;43:415-20.
Indexing Status Subject indexing assigned by NLM MeSH Aged; Community Health Nursing /economics; Cost-Benefit Analysis; Female; Geriatric Nursing /economics; Health Care Costs /statistics & Home Care Services /economics; Humans; Hypertension /economics /nursing; Male; Mexico; numerical data AccessionNumber 22002006845 Date bibliographic record published 30/04/2004 Date abstract record published 30/04/2004 |
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