Cost per QALY (quality-adjusted life year) and lifetime cost of prolonged mechanical ventilation in Taiwan

Abstract

Introduction: Patients who require prolonged mechanical ventilation (PMV) are increasing and producing financial burdens worldwide. This study determines the cost per QALY (quality-adjusted life year), out-of-pocket expenses, and lifetime costs for PMV patients stratified by underlying diseases and cognition levels.

Methods: A nationwide sample of 50,481 patients with continual mechanical ventilation for more than 21 days was collected during 1997-2007. After stratifying the patients according to specific diagnoses, a latent class analysis (LCA) was performed to categorise PMV patients with multiple co-morbidities into several homogeneous groups. The survival functions were estimated for individual groups using the Kaplan-Meier method and extrapolated to 300 months through a semi-parametric method. The survival functions were adjusted using an EQ-5D utility value derived from a convenience sample of 142 PMV patients to estimate quality-adjusted life expectancies (QALE). Another convenience sample of 165 patients was used to estimate the out-of-pocket expenses. The lifetime expenditures paid by the single-payer National Health Insurance (NHI) system and patients' families were estimated by multiplying average monthly expenditures by the survival probabilities and summing the values over lifetime.

Results: PMV therapy costs more than 100,000 U.S. dollars (USD) per QALY for all patients with poor cognition. For patients with partial cognition, PMV therapy costs less than 56,000 USD per QALY for those with liver cirrhosis, intracranial or spinal cord injuries, and 57,000-69,000 USD for patients with multiple co-morbidities under age of 65. The average lifetime cost of PMV was usually below 56,000 USD. The out-of-pocket expenses were often more than one-third of the total cost of treatment.

Conclusions: PMV treatment for patients with poor cognition would cost more than 5 times Taiwan's GDP (gross domestic products), or less cost-effective. The out-of-pocket expenses for PMV provision should also be considered in policy decision.

Figure 1. Flow chart of the computation process for lifetime costs and cost-per-QALY (quality-adjusted life year).

Figure 2. Quality adjusted survival for patients undergoing PMV (prolonged mechanical ventilation) with partial cognition after adjustment for survival function (N = 50,481) with the utility values of quality of life measured with EQ-5D (N = 55).

The result of QALE (quality-adjusted life expectancy) of an average patient was 0.98 QALY by summing the areas under the quality-adjusted survival curve.

Figure 3. The average lifetime healthcare expenditure paid by the National Health Insurance (NHI) for patients undergoing PMV.

(prolonged mechanical ventilation) was calculated by multiplying the monthly average paid by the NHI (N = 50,481) with the corresponding survival probability and then summed up throughout life, as indicated by the shaded areas of the upper panel. The lifetime out-of pocket expense for PMV patients was obtained by multiplying the monthly average out-of pocket expense (estimated by kernel smoothing method on a convenient sample of 165 patients) with the corresponding survival probability and then summed up (shaded areas of the lower panel). The expected lifetime cost of a PMV patient is the total sum of these two shaded areas.

Figure 4. Plot of association between the cost-per-QALY (quality-adjusted life year) gained and the lifetime cost for different diagnosis groups of PMV patients with partial cognition.

, stratified by different specific illnesses [○] and multiple co-morbidities (indicated by sub-age groups, <65[•], 65–74[▪], 75–84[▾], and >84[□] years old). The GDP (gross domestic product) of Taiwan in 2010 was 18,588 US dollars, below which the cost-per-QALY was considered as cost-effective; between 1–3 times the GDP per QALY gained was considered moderate cost-effective, and above 3 times the GDP per QALY gained was not cost-effective. The figure indicates there are many conditions showing a lifetime cost less than 3 times the GDP, although their costs-per-QALY were above that figure.