|The cost effectiveness of 5 interventions to increase mammography adherence in a managed care population
|Saywell R M, Champion V L, Zollinger T W, Maraj M, Skinner C S, Zoppi K A, Muegge C M
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.
Five strategies to improve mammography adherence were examined.
physician reminder letter,
telephone counselling plus physician reminder letter, and
in-person counselling plus physician reminder letter.
Economic study type
The study population comprised women aged 50 to 85 years who had never had breast cancer, and who had not had a mammography in the last 15 months.
The setting was primary care within an HMO. The economic study was conducted in the USA.
Dates to which data relate
The effectiveness and resource use data were gathered from 1994 to 1999. The price year was not reported.
Source of effectiveness data
The effectiveness evidence was derived from a single study.
Link between effectiveness and cost data
The costing was conducted prospectively on the same sample of women as that used in the effectiveness analysis.
Power calculations were conducted after the sample was enrolled. These suggested that the whole study sample was powered to detect a difference in adherence rates of about 15 percentage points. Women were identified from all eligible HMO members who agreed to participate in the study (approximately 39% of all those eligible). The main reason for refusal was unavailability to participate in a 2-year intervention study. The whole sample comprised 652 participants:
108 women in group 1 (no intervention),
93 women in group 2 (telephone counselling),
111 women in group 3 (in-person counselling),
110 women in group 4 (physician reminder letter),
115 women in group 5 (telephone counselling plus physician reminder letter), and
114 women in group 6 (in-person counselling plus physician reminder letter). The mean age was 61.2 years. The proportion of women aged between 50 and 59 years was 53.7%, while 23.5% of the sample was aged 70 years or older. The four sub-groups considered were women who were or were not planning to have a mammography in the next 6 months (contemplators versus pre-contemplators), and women with or without a history of prior mammography (history versus no history of mammograms).
This was a prospective, randomised controlled trial that was conducted at several primary care centres in a large midwestern HMO. The method of randomisation was not reported. The women were followed for 6 months. At the end of the study period, 628 (95.9%) had complete follow-up data.
Analysis of effectiveness
The analysis of the clinical study appears to have been conducted on the basis of treatment completers only. The primary outcome measure used was the adherence rate. A logistic regression model, with adherence as the dependent variable and groups as the independent variables, provided the odds ratio (OR) with confidence intervals (CIs) for group differences in adherence at 6 months post-intervention. The baseline comparability of the study groups was not discussed.
In the overall study group, the OR of each strategy relative to no intervention (group 1) was:
1.72 (CI: 0.964 - 3.054; p=0.067) for group 2,
2.66 (CI: 1.529 - 4.610; p=0.001) for group 3,
2.02 (CI: 1.165 - 3.514; p=0.012) for group 4,
2.21 (CI: 1.282 - 3.824; p=0.004) for group 5, and
3.34 (CI: 1.919 - 5.801; p=0) for group 6.
In the overall study group, the adherence rate was 31.5% in group 1, 44.1% in group 2, 55% in group 3, 48.2% in group 4, 50.4% in group 5, and 60.5% in group 6. When the basic comparator was no intervention (group 1), the adherence rates in groups 2 to 6 were significantly higher than those in group 1. When the comparator was group 6, only group 3 was not significantly different.
In the sub-group of contemplators, the adherence rate was 52.4% in group 1, 48.4% in group 2, 62.3% in group 3, 59.6% in group 4, 65.6% in group 5, and 74.5% in group 6. Only the adherence rate in group 6 was significantly different from that in group 1.
In the sub-group of pre-contemplators, the adherence rate was 18.5% in group 1, 42.4% in group 2, 44.9% in group 3, 37.5% in group 4, 30.6% in group 5, and 49.2% in group 6. Only the adherence rate in group 6 was significantly different from that in group 1. The adherence rates in groups 2, 3 and 4 were not significantly different from those in group 6.
In the sub-group of women with a history of mammography, the adherence rate was 33.7% in group 1, 50% in group 2, 56.4% in group 3, 57.2% in group 4, 52.4% in group 5, and 61.2% in group 6. The adherence rates in groups 2 to 6 were significantly different from those in group 1.
In the sub-group of women without a history of mammography, the adherence rate was 16.7% in group 1, 22.2% in group 2, 33.3% in group 3, 13.3% in group 4, 30% in group 5, and 58.3% in group 6. Only the adherence rate in group 6 was significantly different from that in group 1.
The effectiveness analysis showed that the adherence rates of interventions 2 to 6 were generally higher than those in the no intervention group. In general, in-person counselling and physician reminder letter was the most effective intervention in all groups of patients.
Measure of benefits used in the economic analysis
The summary benefit measure used was the adherence rate. This was derived directly from the effectiveness analysis.
Discounting was not relevant since the costs were incurred during a 6-month timeframe. The unit costs were not presented separately from the quantities of resources used. The health services included in the economic evaluation were the variable expenses associated with labour, and supplies and equipment. Variable expenses covered wages and benefits of project personnel involved with counselling, contacting, interviewing and assessing study participants, and sending reminders. Equipment and supplies covered printing, postage and telephone charges. The fixed costs were considered a minor component and were not included in the analysis. The cost/resource boundary of the HMO was considered. The quantities of resources used were derived from actual data associated with the sample of patients included in the effectiveness study. The source of the data was not reported explicitly. The price year was not reported.
Statistical analysis of costs
The costs were treated deterministically.
The indirect costs were not considered.
Sensitivity analyses were not carried out.
Estimated benefits used in the economic analysis
See the 'Effectiveness Results' section.
The mean intervention costs were $0 with strategy 1, $12.52 with strategy 2, $14.21 with strategy 3, $1.28 with strategy 4, $13.58 with strategy 5, and $18.03 with strategy 6.
Synthesis of costs and benefits
The average cost-effectiveness ratios were calculated to combine the costs and benefits of the interventions evaluated. An incremental analysis was not conducted. In the overall group of patients, the average cost per 1% improvement in adherence rate in comparison with strategy 1, was $0.99 with strategy 2, $0.60 with strategy 3, $0.08 with strategy 4, $0.72 with strategy 5, and $0.62 with strategy 6. The authors stated that intervention 6 was the most cost-effective, followed by intervention 3. Similar results were obtained in the sub-group analyses.
Any of the five interventions evaluated in the study was better than no intervention when considering the effectiveness alone. When economic aspects were considered, both in-person counselling and in-person counselling plus physician reminder letter were cost-effective, as the cost-differences were modest and the adherence rates were high with both approaches. Individual patient characteristics, such as history of mammography or stage of contemplation, permitted selection of the most appropriate strategy in sub-groups of patients.
CRD COMMENTARY - Selection of comparators
The rationale for the choice of the comparator was clear. No intervention was selected to assess the active value of the other interventions, which reflected possible combinations of strategies to enhance mammography adherence. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness
The effectiveness evidence was derived from a clinical trial, which was appropriate for the study question. This was the long-term analysis of a previous trial carried out by the same authors. Therefore, some of the details of the analysis, such as the method of randomisation and outcome assessment, were not reported. The baseline comparability of the study groups was not discussed. The impact of each intervention on the main outcome measure was assessed statistically. The evidence came from several centres but, it was unclear whether the study sample was representative of the study population since less than 40% of all eligible women agreed to participate. The main reason for refusal was reported. Power calculations were conducted prospectively. These showed that the sample had sufficient power to detect statistically significant differences between the groups. However, as the authors acknowledged, some women could have returned to the primary care physician during the study period and, thus, could have received a repeated reminder to have a mammography.
Validity of estimate of measure of benefit
The summary benefit measure was derived directly from the effectiveness analysis. Since it was specific to the study intervention it cannot, therefore, be compared with the benefits of other health care interventions. The impact of the interventions on survival or quality of life was not assessed.
Validity of estimate of costs
The perspective of the study was implicitly stated. Only those costs strictly related to the implementation of the interventions aimed at improving mammography adherence were considered in the analysis. The costs related to the prevention of cancer were not considered, although they could have been relevant from a wider perspective. The dates during which the resource use data were gathered were reported, but the price year was not given. Therefore, reflation exercises in other settings would be difficult. The unit costs and the quantities of resources used were not presented separately. The costs were specific to the study setting and no sensitivity analyses were conducted. The costs were treated deterministically.
The authors did not make extensive comparisons of their findings with those from other studies. They reported only the results of their previous study. The issue of the generalisability of the study results to other settings was not addressed. In effect, sensitivity analyses were not conducted, which affected the external validity of the analysis. The use of incremental cost-effectiveness ratios would have been useful.
Implications of the study
The study results suggested that HMOs could tailor interventions designed to provide reminders of mammography screening depending on member characteristics. Further studies should be conducted in different study populations to corroborate the findings of the current study.
Source of funding
Funded by the National Center for Nursing Research and the National Cancer Institute (NIH-RO1 CA58606).
Saywell R M, Champion V L, Zollinger T W, Maraj M, Skinner C S, Zoppi K A, Muegge C M. The cost effectiveness of 5 interventions to increase mammography adherence in a managed care population. American Journal of Managed Care 2003; 9(1): 33-44
Other publications of related interest
Saywell RM Jr, Champion VL, Skinner CS, et al. Cost-effectiveness comparison of 5 interventions to increase mammography screening. Preventive Medicine 1999;29:374-82.
Wagner T. The effectiveness of mailed patient reminders on mammography screening: a meta-analysis. American Journal of Preventive Medicine 1998;14:64-70.
Subject indexing assigned by NLM
Aged; Aged, 80 and over; Breast Neoplasms /prevention & Cost-Benefit Analysis; Diagnostic Tests, Routine /utilization; Directive Counseling /economics /methods; Female; Health Maintenance Organizations /economics /organization & Health Services Research; Humans; Logistic Models; Mammography /utilization; Middle Aged; Midwestern United States; Patient Compliance /statistics & administration; control; numerical data
Date bibliographic record published
Date abstract record published