OBJECTIVE—To estimate the lifetime health and economic effects of optimal prevention and treatment of the diabetic foot according to international standards and to determine the cost-effectiveness of these interventions in the Netherlands.

RESEARCH DESIGN AND METHODS—A risk-based Markov model was developed to simulate the onset and progression of diabetic foot disease in patients with newly diagnosed type 2 diabetes managed with care according to guidelines for their lifetime. Mean survival time, quality of life, foot complications, and costs were the outcome measures assessed. Current care was the reference comparison. Data from Dutch studies on the epidemiology of diabetic foot disease, health care use, and costs, complemented with information from international studies, were used to feed the model.

### Health and economic outcomes

All cohorts of patients simulated for the different scenarios of guidelines care resulted in improved life expectancy, QALYs gained, and reduced incidence of foot ulcers and LEA compared with standard care. The largest effects on these outcomes were obtained when patients received IGC + OFC. When comparing the independent health effects of the two guidelines strategies, OFC resulted in a greater reduction in ulcer and amputation rates than IGC. Moreover, patients who received IGC + OFC showed approximately the same LEA incidence as patients who received OFC alone. The LEA decrease obtained was proportional to the level of foot ulcer reduction attained.

The mean total lifetime costs of a patient under either of the three guidelines care scenarios ranged from $4,088 to$4,386. For patients receiving IGC + OFC, these costs resulted in <$25,000 per QALY gained (relative to standard care). For patients receiving IGC alone, the ICER obtained was$32,057 per QALY gained, and for those receiving OFC alone, this ICER ranged from $12,169 to$220,100 per QALY gained, depending on the level of ulcer reduction attained.

Figure 2 is a graphical representation of the additional costs, QALYs gained, and ICER of the three guidelines care scenarios compared with standard care. All levels of foot ulcer reduction (10–90%) considered in the sensitivity analysis are represented. Also shown are the results of the sensitivity analyses performed on the QALY weights and length-of-stay input parameters. The results of the simulations for the combined scenario (IGC + OFC) were used to illustrate the effects of these variations (curves to the right). Results are shown for both input parameters varied simultaneously and separately (Fig. 3).

ICERs of <$25,000 were obtained for levels of preventive foot care of ≥10% for patients under IGC + OFC and for levels of preventive foot care of >40% for patients receiving OFC alone (Table 2). ### Sensitivity analyses Increasing the effectiveness of preventive foot care in patients under OFC and IGC + OFC resulted in more QALYs gained, lower costs, and a more favorable ICER. The results of the simulations for the combined scenario (IGC + OFC) were rather insensitive to changes in utility weights and costing parameters. Similar results were obtained for parameter variations in the other two scenarios (IGC and OFC separately). The results of this study suggest that IGC + OFC reduces foot ulcers and amputations and leads to an improvement in life expectancy. Greater health benefits are obtained with higher levels of foot ulcer prevention. Although care according to guidelines increases health costs, the cost per QALY gained is <$25,000, even for levels of preventive foot care as low as 10%. ICERs of this order are cost-effective according to the stratification of interventions for diabetes recently proposed (32).

OFC strategy alone is only cost-effective at levels of preventive foot care >40%. In a previous economic study performed in Sweden (13), intensified foot care intervention was cost-effective when a 25% reduction in incidence of foot ulcers and amputations was assumed. This difference in the level of preventive foot care between their study and our study, albeit not large, may be attributed to differences in model architecture, follow-up period, and information used in the models, including country-specific parameters such as incidence of foot complications, prevalence of foot wounds, and costs.

The cost-effectiveness of IGC alone was estimated to be $32,057 per QALY and the reduction in incidence of LEA was estimated to be 4.4%. Our results are comparable to those reported by the Centers for Disease Control and Prevention (CDC) group (8), in which an ICER of$41,384 and an LEA reduction of ∼3% were reported. IGC falls into the category of a possibly cost-effective intervention in the management of the diabetic foot. Although it does not produce significant reduction in foot ulcers and LEA, its effectiveness resides in the slowing of neuropathy progression rates.

Extrapolating our results to a practical situation, if IGC + OFC was to be given to all diabetic patients in the Netherlands, with the aim of reducing LEA by 50% (St. Vincent’s declaration), the cost per QALY gained would be $12,165 and the cost for managing diabetic ulcers and amputations would decrease by 53 and 58%, respectively. From a policy perspective, this is clearly cost-effective and cost saving compared with current care. From a clinical perspective, this goal is achievable considering that LEA reductions of 49–85% have been reported in the literature for strategies containing only foot care preventive measures (6). For OFC alone, these results would be achieved at an ICER of$22,812, which is twice the ratio seen for the combined scenario.

The results of our study are supported by the robustness of the model. The agreement of the epidemiologic outputs with known data on incidence and prevalence of the diabetic foot provides evidence of the model’s ability to adequately reflect disease progression. In building the model, great effort was put into collecting updated, representative, and consistent information; therefore, the conclusions that can be drawn from it are valid and the probability for bias is small. Although the input parameters used were based on a Dutch setting, the model’s structure has worldwide applicability.

In conclusion, guidelines care comprising metabolic and foot care interventions combined is cost-effective and may even be cost saving in the management of the diabetic foot in the Netherlands. A valid and comprehensive Markov model that can be used for future cost-effectiveness analysis of diabetic foot disease prevention has been developed.

Figure 1—

Health states and transition paths. Not shown is the chance of death for all health states. The permanency in the ischemic state refers to treated ischemia. DFR1, no neuropathy; DFR2, sensory neuropathy; DFR3, sensory neuropathy and deformity or peripheral vascular disease.

Figure 1—

Health states and transition paths. Not shown is the chance of death for all health states. The permanency in the ischemic state refers to treated ischemia. DFR1, no neuropathy; DFR2, sensory neuropathy; DFR3, sensory neuropathy and deformity or peripheral vascular disease.

Figure 2—

Costs, effects, and sensitivity analysis results for guidelines care scenarios compared with standard care. Curves correspond to foot ulcer reduction levels of 10–90% (10% intervals). Black symbols represent simulation results obtained using reference input parameters; white symbols represent simulation results obtained using alternative input parameters results. •, IGC point estimate; ▴, OFC curve; ▪, IGC + OFC curve; ▵, IGC + OFC curve using alternative utility weights; ○, IGC + OFC curve using alternative costs; □, IGC + OFC curve using alternative utility weights and costs simultaneously.

Figure 2—

Costs, effects, and sensitivity analysis results for guidelines care scenarios compared with standard care. Curves correspond to foot ulcer reduction levels of 10–90% (10% intervals). Black symbols represent simulation results obtained using reference input parameters; white symbols represent simulation results obtained using alternative input parameters results. •, IGC point estimate; ▴, OFC curve; ▪, IGC + OFC curve; ▵, IGC + OFC curve using alternative utility weights; ○, IGC + OFC curve using alternative costs; □, IGC + OFC curve using alternative utility weights and costs simultaneously.

Figure 3—

Six-month costs per health state for standard care. Not shown for the amputation states are the one-time costs for surgery and hospitalization. OM, osteomyelitis.

Figure 3—

Six-month costs per health state for standard care. Not shown for the amputation states are the one-time costs for surgery and hospitalization. OM, osteomyelitis.

Table 1—

Six-month transition probabilities and input values for standard care

From ↓ To →Transition probabilities
UtilitiesCosts
DFR1DFR2DFR3PreulcerSuperficial ulcerSuperficial infectionDeep ulcerAbscess/osteomyelitisIschemiaHealedPost minor amputationPost major amputationDeathReferences
DFR1 95.7 1.99 — 0.2 0.02 0.006 — — — — — — 17–22,24 0.84 108
DFR2 — 90 0.6 0.06 0.01 0.01 0.04 — — — — 4.5 17,19–22,24 0.74 108
DFR3  — 94.8 0.03 0.18 0.11 0.11 0.20 0.07 — — — 4.5 17,19,20,22–24 0.74 108
Preulcer — — — — 98* — — — — — — — 2* 23,24 0.75 108
95.5        4.5
90        10
Superficial ulcer — — — — — — — — — 98* — — 2* 23,24 0.75 874
95.5   4.5
90   10
Superficial infection — — — — — — — — 87.5* — — 4.5* 22–24 0.70 1,181
82   10
Deep ulcer — — — — — — — — — 95.5 — — 4.5 22–24 0.75 1,872
90   10
Abscess/osteomyelitis — — — — — — — 16.5 — 21.5 20.5 31.5 10 22–24 0.59 4,834
Ischemia — — — — — — — — 22.3 22.7 17.4 27.2 10 22–24 0.59 2,621
Healed — — — 0.21 1.3 0.77 0.78 1.43 0.54 84.9 — — 10 17,19,20,23,24 0.68 108
Postminor amputation — — — 0.21 1.3 0.77 0.78 1.43 0.54 — 76 17 1.69 17,19,20,23,25 0.68 923
Postmajor amputation — — — — — — — — — — — 89 11 25 0.62 1,325
From ↓ To →Transition probabilities
UtilitiesCosts
DFR1DFR2DFR3PreulcerSuperficial ulcerSuperficial infectionDeep ulcerAbscess/osteomyelitisIschemiaHealedPost minor amputationPost major amputationDeathReferences
DFR1 95.7 1.99 — 0.2 0.02 0.006 — — — — — — 17–22,24 0.84 108
DFR2 — 90 0.6 0.06 0.01 0.01 0.04 — — — — 4.5 17,19–22,24 0.74 108
DFR3  — 94.8 0.03 0.18 0.11 0.11 0.20 0.07 — — — 4.5 17,19,20,22–24 0.74 108
Preulcer — — — — 98* — — — — — — — 2* 23,24 0.75 108
95.5        4.5
90        10
Superficial ulcer — — — — — — — — — 98* — — 2* 23,24 0.75 874
95.5   4.5
90   10
Superficial infection — — — — — — — — 87.5* — — 4.5* 22–24 0.70 1,181
82   10
Deep ulcer — — — — — — — — — 95.5 — — 4.5 22–24 0.75 1,872
90   10
Abscess/osteomyelitis — — — — — — — 16.5 — 21.5 20.5 31.5 10 22–24 0.59 4,834
Ischemia — — — — — — — — 22.3 22.7 17.4 27.2 10 22–24 0.59 2,621
Healed — — — 0.21 1.3 0.77 0.78 1.43 0.54 84.9 — — 10 17,19,20,23,24 0.68 108
Postminor amputation — — — 0.21 1.3 0.77 0.78 1.43 0.54 — 76 17 1.69 17,19,20,23,25 0.68 923
Postmajor amputation — — — — — — — — — — — 89 11 25 0.62 1,325

Data for transition probabilities are percentages.

*

Risk 1;

Risk 2–3;

Risk 4. Transition from DFR1 to DFR2 corresponds to baseline incidence rates. Discrepancies due to rounding. Costs expressed as 1999 U.S. dollars.

Table 2—

Clinical and economic outcomes of standard care and guidelines care simulations

Life expectancyStandard careGuideline care
IGC10% foot lesion reduction
90% foot lesion reduction
OFCIGC + OFCOFCIGC + OFC
Life expectancy (years) 8.14 8.21 8.15 8.23 8.33 8.41
SD of life expectancy (years) 0.43 0.43 0.43 0.43 0.44 0.44
Difference in life expectancy NA 0.07 0.01 0.09 0.19 0.27
QALY 6.49 6.56 6.50 6.58 6.65 6.74
SD of QALY 0.34 0.35 0.34 0.35 0.35 0.35
Difference in QALY NA 0.07 0.01 0.09 0.16 0.25
Total lifetime costs 2,142 4,386 4,343 4,352 4,088 4,107
SD of total lifetime costs 259 337 329 323 232 232
Difference in total lifetime costs NA 2,244 2,201 2,210 1,946 1,965
ICER NA 32,057 220,100 24,556 12,163 7,860
Cumulative incidence of ulcers (%) 17.8 17.7 15.8 15.84 1.31 1.28
Cumulative incidence of amputations (%) 3.62 3.46 3.28 3.24 0.25 0.24
Ulcer reduction (%) NA 0.56 11.2 11.2 92.7 92.8
Amputation reduction (%) NA 4.4 9.4 10.5 93.1 93.4
Life expectancyStandard careGuideline care
IGC10% foot lesion reduction
90% foot lesion reduction
OFCIGC + OFCOFCIGC + OFC
Life expectancy (years) 8.14 8.21 8.15 8.23 8.33 8.41
SD of life expectancy (years) 0.43 0.43 0.43 0.43 0.44 0.44
Difference in life expectancy NA 0.07 0.01 0.09 0.19 0.27
QALY 6.49 6.56 6.50 6.58 6.65 6.74
SD of QALY 0.34 0.35 0.34 0.35 0.35 0.35
Difference in QALY NA 0.07 0.01 0.09 0.16 0.25
Total lifetime costs 2,142 4,386 4,343 4,352 4,088 4,107
SD of total lifetime costs 259 337 329 323 232 232
Difference in total lifetime costs NA 2,244 2,201 2,210 1,946 1,965
ICER NA 32,057 220,100 24,556 12,163 7,860
Cumulative incidence of ulcers (%) 17.8 17.7 15.8 15.84 1.31 1.28
Cumulative incidence of amputations (%) 3.62 3.46 3.28 3.24 0.25 0.24
Ulcer reduction (%) NA 0.56 11.2 11.2 92.7 92.8
Amputation reduction (%) NA 4.4 9.4 10.5 93.1 93.4

Costs expressed as 1999 U.S. dollars. SD of mean was derived using 10,000 Monte Carlo simulations, each consisting of 100 individuals.

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