Aim
The primary aim of the economic evaluation was to compare the cost incurred over 28 days with respect to primary care contacts plus A&E contacts (using primary outcome data) for GPT, NT and UC, in people requesting same-day appointments in general practice. The perspective of the analysis is that of the UK NHS, i.e. third-party payer.
Method
Intervention cost
Resource use associated with the set-up and delivery of the triage interventions (GPT, NT) comprised initial training costs (set-up), CDSS and licence costs, and staff time spent on delivery of the triage contact. These resource use areas were identified during the pilot study.
Training
Staff time spent at training events, required for set up of the triage intervention, was captured by a within-trial data collection form (completed by the trial researcher). This was a written record of all staff
time (including trainers and trainees) at all relevant training events by staff grade or type, and by practice (seeTraining practices in the two triage systems, above, for an outline of the training schedule in each intervention).
Software and equipment
When comparing triage interventions with UC, pilot study research identified the only additional resource here (i.e. software and equipment) to be the CDSS for the nurse-led, computer-supported triage
intervention. The costs of the CDSS and licence fees (required for first year and subsequent years) in each of the NT practices were documented (with information from supplier) within trial.
Triage staff time
Staff time (GP, nurse) used on the delivery of the triage contact (patient contact time) was recorded using the within-trial‘Clinician Form’(seeData collection and management). Data collection included staff type by grade, and start time and end time for each triage contact was recorded.
Resource-use data were combined with unit cost data, and market prices (software, licence fees) to estimate the mean cost per triage contact. Costs were reported using 2012 cost data, or with cost data uprated to 2012 costs where required. Costs associated with training and other set-up costs (computer support system) for triage interventions were estimated at a mean cost per practice, and an estimate of the expected number of same-day contacts per practice per year was used to spread the costs across an expected patient group (number of patients requesting same-day appointment per practice). Assumptions on these data and other areas of uncertainty are tested using sensitivity analyses.
Economic outcome: costs of primary care contacts (plus accident and emergency) over 28 days
Primary economic (cost) analyses are undertaken using data collected on the primary outcome, contacts taking place in primary care over 28 days, collected within trial at participant level using a case
note review.
Primary care and related contacts by type of contact, as included in the POM, are detailed above (seePrimary outcome measure). Trial data on service use were combined with unit cost data (Table 4) to estimate a mean 28-day cost for primary care service use, for each of the trial arms. Most unit cost data were taken from those reported by Curtis38(PSSRU unit costs), with other cost data sourced from credible
national data sources (seeTable 4). Contacts recorded as GP or general unspecified (n=30) are treated as GP in surgery consultation, for the purpose of cost analyses. Contacts recorded as‘Nurse contact unspecified’(n=15) were treated as‘Nurse in surgery’consultation for the purpose of cost analyses. Exploratory analyses report data (primary outcome) on the resource use and costs for‘same-day’care for participants by intervention arm. This analysis includes the data on index contact and other resource use on the same day as the index contact. These exploratory analyses used unit costs for triage contacts as derived from trial data (as above), and published unit cost data on other contacts by type. A sample of data was collected within the trial to provide information on the duration of GP and nurse face-to-face consultations following a triage contact. These data were considered in the context of exploratory analyses of same-day care, and costs of same-day care.
Data analysis: presentation of analysis
Economic analyses were consistent with the methods described for the main statistical analyses (effectiveness outcomes data). The primary economic analyses were based on the ITT trial data (as described above). Data are presented descriptively, and thereafter cost analyses use a random-effects regression model taking account of the hierarchical nature of the study design (i.e. allocation by practice) and allowing for adjustment for practice-level minimisation variables (geographical location, deprivation level and size of practice) and participant-level covariates for age and gender. Data were initially explored using a GLM fitted with the appropriate choice of family and link function according to the type of data
and its properties. Based on findings from these analyses (using GLM methods), main analyses are presented using a hierarchical multilevel model, assuming normally distributed total cost data. The ICC is reported for primary cost analyses.
The primary economic analyses present estimates of the mean cost of care across each of the trial arms, as above. Primary analyses report on participants with data on the POM, i.e. a complete case analysis. Regression-based methods (as above) were used to estimate difference in costs for care between trial arms, based on the 28-day data included in the primary outcome. CIs (95%) are estimated using parametric methods. Typically, where a sample has a large number of observations, as in this case (with>16,000 participants in ESTEEM), incorporating central limit theorem implies parametric tests are appropriate and may be used for analysis of resource use and cost data. Item-level costs are presented descriptively, consistent with the data presentation in the effectiveness analyses.
In secondary analyses, a per-protocol analysis has been performed (for the primary economic outcome only), including only patients who received the triage intervention, this being consistent with the main statistical analysis plan and effectiveness analyses. As no difference is reported on EQ-5D single index values (quality-adjusted life-year weights), by treatment allocation, no exploratory analyses are considered on cost-effectiveness analyses using this outcome.
TABLE 4 Unit cost data (2012) with data sources for the base case
Resource use unit Unit cost (£) Source
GP telephone triage intervention
14.03 ESTEEM trial (seeTable 26)
Nurse telephone triage intervention
7.62 ESTEEM trial (seeTable 26)
GP consultation (in surgery) 43.00 Per contact unit cost from Curtis,38
based on consultation lasting 11.7 minutes, including direct care staff costs with qualifications
GP telephone consultation 26.00 Per contact unit cost from Curtis,38based on telephone consultation of
7.1 minutes, including direct care staff costs with qualifications GP home visit
(within surgery hours)
110.00 Per contact unit cost from Curtis,38
based on home visit lasting 23.4 minutes (including travel time/cost)
Practice nurse consultation (in surgery)
13.64 Derived using cost per minute from Curtis.38Assumes 15.5-minute nurse
consultation × unit cost per hour/minute (£53/£0.88, including qualifications costs) for face-to-face contact
Practice nurse telephone consultation
5.28 Derived using cost per minute from Curtis.38
Assumes 6 minutes/ telephone consultation cost [duration from advance nurse] × unit cost per hour/minute (£53/£0.88, including qualifications costs) for face-to-face contact
Practice nurse home visit (within surgery hours)
22.00 Derived using cost per minute from Curtis.38Assumes 25 minutes/home
visit cost [duration from advanced nursing professional] × unit cost per hour/minute (£53/£0.88, including qualifications costs) for
face-to-face contact Walk-in centre attendance
(doctor/nurse/unspecified)
41.00 Per contact unit cost from Curtis38
A&E walk-in service (not admitted)
Out-of-hours contact
(doctor/nurse/unspecified)a
61.14 Primary Care foundation, 2013 (www.primarycarefoundation.co.uk)
A&E: doctor/nurse/unspecified 112.00 Per A&E attendance, not admitted–national average (weighted
averages irrespective of occupation) from Curtis38
a Unit cost based on average cost per case, including all overheads and oncosts associated with provision of out-of-hours care. Obtained from survey of primary care trusts in England. URL: www.primarycarefoundation.co.uk (accessed 5 November 2014).
Sensitivity analyses were undertaken against the primary analyses to explore the implications of uncertainty in data used and the assumptions made within the primary analyses. Sensitivity analyses included an analysis of primary outcome data (total 28-day cost), with missing data imputed via multiple imputation methods (as used in effectiveness analyses).
Results from exploratory analyses are presented descriptively, and with regression-based methods used to provide comparative analyses where appropriate.
Results are presented in tabular format using mean estimates of resource use and cost, with summary measures on the distribution around the mean. A broader presentation of findings are presented in tabular format consistent with the approach described as cost–consequences analyses, presenting estimates of costs alongside the expected impacts associated with interventions, for example safety outcomes, health status and measures of patient experience. Cost–consequences analyses are regarded as a form of full economic evaluation, even though the costs and outcomes are not brought together in a cost-effectiveness ratio.61