| Literature DB >> 34183438 |
Carl Bonander1,2, Robin Holmberg2,3, Johanna Gustavsson2,3, Mikael Svensson4.
Abstract
BACKGROUND: Slipping on snow or ice poses a significant health risk among older adults in Sweden. To combat this problem, about 80 Swedish municipalities have distributed ice cleats to older citizens (65+ years old) over the last decade. This paper details a cost-benefit analysis of such programmes.Entities:
Keywords: economic analysis; fall; older people; uptake/adherence
Mesh:
Substances:
Year: 2021 PMID: 34183438 PMCID: PMC8938667 DOI: 10.1136/injuryprev-2021-044203
Source DB: PubMed Journal: Inj Prev ISSN: 1353-8047 Impact factor: 2.399
Model parameters, probability distributions and data sources for the decision-analytical model for economic evaluation of municipal ice cleat distribution programmes
| Parameter | Average (range, if applicable) | SE | Distribution (probabilistic sensitivity analysis) | Data source |
| Annual number of snow-related or ice-related fall injuries at baseline as a function of population size and climate ( | 21.6 (2.7, 472.6) | Municipality-specific SE from regression prediction | Lognormal | Municipality-specific and age-specific data from National Patient Register |
| Initial change in ice cleat use as a function of climate ( | 0.25 (0.09, 0.35) | Municipality-specific SE from regression prediction | Logit-normal | National survey (random sample, n=4608 aged 65+) conducted in 2007 by the Swedish Civil Contingencies Agency* |
| Compliance over time, multiplicative scaling factor ( | { | Not available | None | Calibrated* simulation model to results from quasi-experimental evaluation in Gothenburg |
| Effect of ice cleat use (RR), log scale | −0.799 | 0.333 | Lognormal | Randomised controlled trial |
| Total programme cost per purchased ice cleat pair in 2018 Euros ( | 1.998 | 0.100 | Lognormal | Electronic survey sent to all Swedish municipalities (n=34 responses with cost data)* |
| Benefit per averted injury in 2018 Euros | 329 783 | Not available | None | Swedish Transport Administration |
*Additional information on data and estimation is provided in the online supplemental file.
†RR for falls (with or without an injurious outcome). Estimate for injurious falls was 0.1 (95% CI: 0.02 to 0.53) but was only based on a total of 11 events (one in the treatment group and 10 in the control group). Our preferred estimate (for falls) is supported by more data and is more conservative.
RR, relative risk.
Results from the deterministic sensitivity analysis
| Scenario | Expected NPV | Benefit-to-cost ratio | Pr(cost-beneficial), |
| Base-case result (for reference) | 1192.62 (1061.77, 1338.12) | 87.44 (77.69, 98.31) | 0.991 (0.989, 0.992) |
| Increase cost to highest reported cost per procured ice cleat (€27.9 per pair) | 1141.55 (1012.03, 1286.41) | 23.55 (20.93, 26.49) | 0.988 (0.981, 0.99) |
| Reduce WTP per QALY gained to match healthcare sector (€50 000 per QALY) | 245.25 (217.05, 276.71) | 18.98 (16.85, 21.35) | 0.987 (0.977, 0.989) |
| Reduce baseline risk by a factor of 0.59 to match warmest year between 2001 and 2019 | 688.77 (611.34, 774.01) | 51.5 (45.72, 57.89) | 0.990 (0.987, 0.991) |
| Reduce initial compliance rate from 25% to 5% on average | 281.86 (245.93, 325.25) | 21.66 (18.96, 24.91) | 0.986 (0.978, 0.989) |
| Reduce RR of ice cleat use by half (RR=0.73) | 405.86 (361.81, 453.98) | 30.75 (27.44, 34.38) | 0.989 (0.985, 0.991) |
| Reduce RR of ice cleat use by three quarters (RR=0.875) | 166.5 (148.28, 186.02) | 13.21 (11.82, 14.69) | 0.985 (0.974, 0.988) |
| Limit intervention effect to first year | 443.49 (391.82, 502.75) | 33.51 (29.64, 37.93) | 0.989 (0.985, 0.991) |
| Increase discount rate to 5% | 1160.59 (1032.03, 1303.57) | 86.09 (76.49, 96.80) | 0.991 (0.989, 0.992) |
| Cost-minimisation analysis (ignore WTP per averted injury) | −0.65 (−1.76, 0.62) | 0.95 (0.85, 1.07) | 0.405 (0.004, 0.720) |
The table shows the results from additional scenarios to test the sensitivity of the base-case results to deterministic variations in key assumptions and input parameters. Details and rationale for each scenario is presented in the online supplemental file to this article. The estimates in the table reflect totals or means for all Swedish municipalities averaged across 100 000 simulations, with the 2.5th and 97.5th percentiles of the simulated estimates in parentheses unless otherwise noted. The simulations are run over a 4-year period. The net present value (NPV) is given by Equation (1), which, if positive, implies that the interventions are cost-beneficial. The benefit-to-cost ratio expresses how much the estimated benefits outweigh the costs in relative terms. Pr(cost-beneficial) is the proportion of the 100 000 simulations in which the NPV is positive, which gives an overall estimate of how likely it is that an ice cleat programme would be cost-beneficial according to the model (for this parameter, the numbers in parentheses reflect the least to most certain municipal-specific estimate).
Pr, probability; QALY, quality-adjusted life years; RR, relative risk; WTP, willingness to pay.
Results from the cost–benefit analysis under base-case and pessimistic scenarios in which ice cleat programmes are implemented in all Swedish municipalities compared with a business-as-usual scenario without ice cleat programmes
| Estimate | Base-case* | Pessimistic scenario† |
| Incremental benefit, total (million Euros) | 1192.62 (1061.77, 1338.12) | 89.16 (78.05, 101.09) |
| Incremental cost, total (million Euros) | 13.64 (13.35, 13.94) | 27.28 (26.70, 27.88) |
| Net present value, total (million Euros) | 1178.98 (1048.42, 1324.18) | 61.89 (52.35, 73.21) |
| Benefit-to-cost ratio | 87.44 (77.69, 98.31) | 3.27 (2.89, 3.71) |
| Percentage point change in ice cleat users over 4 years, mean | 15.02 (14.96, 15.09) | 3.00 (2.99, 3.02) |
| Expected number of injuries without programmes, total | 25 192 (24 436, 26 008) | 25 192 (24 440, 26 009) |
| Expected number of injuries with programmes, total | 21 441 (20 681, 22 253) | 24 921 (24 176, 25 731) |
| Injuries averted, total | 3751 (3339, 4209) | 270 (240, 307) |
| Relative intervention effect (rate ratio) | 0.85 (0.83, 0.87) | 0.99 (0.99, 0.99) |
| Absolute intervention effect (rate difference, 100 000 person-years) | −50.96 (–45.36, –57.18) | −3.67 (−3.26, 4.17) |
| Pr(cost-beneficial), mean (min–max) | 0.991 (0.989, 0.992) | 0.915 (0.675, 0.963) |
The estimates in the table reflect totals or means for all Swedish municipalities averaged across 100 000 simulations, with the 2.5th and 97.5th percentiles of the simulated estimates in parentheses unless otherwise noted. The simulations are run over a 4-year period. The incremental benefits and costs reflect differences between a scenario where all municipalities have implemented ice cleat programmes versus a business-as-usual scenario. The net present value (NPV) is given by Equation (1), which, if positive, implies that the interventions are cost-beneficial. The benefit-to-cost ratio expresses how much the estimated benefits outweigh the costs in relative terms. The remaining estimates reflect estimated effects on the average change in ice cleat users and on injury rates. Pr(cost-beneficial) is the proportion of the 100 000 simulations in which the NPV is positive, which gives an overall estimate of how likely it is that an ice cleat programme would be cost-beneficial according to the model (for this parameter, the numbers in parentheses reflect the least to most certain municipal-specific estimate).
*Scenario using the best available estimates from table 1.
†Doubled costs, increase in ice cleat use limited to the first year, halved initial compliance and halved effect of ice cleats (compared with the base-case scenario).
Figure 1Maps of Sweden’s 290 municipalities that illustrate the geographical variation in (A) estimated benefit-to-cost ratios from our economic simulations (base-case scenario), (B) baseline snow-related or ice-related fall injury rates per 100 000 person-years, (C) the estimated proportion of ice cleat users per municipality without ice cleat distribution programmes and (D) the estimated proportion of the population susceptible to change as a consequence of an ice cleat distribution programme (non-users with a positive attitude towards the efficacy of ice cleats).