Costs and expected gain in lifetime health from intensive care versus general ward care of 30,712 individual patients: a distribution-weighted cost-effectiveness analysis

Abstract

Background: Clinicians, hospital managers, policy makers, and researchers are concerned about high costs, increased demand, and variation in priorities in the intensive care unit (ICU). The objectives of this modelling study are to describe the extra costs and expected health gains associated with admission to the ICU versus the general ward for 30,712 patients and the variation in cost-effectiveness estimates among subgroups and individuals, and to perform a distribution-weighted economic evaluation incorporating extra weighting to patients with high severity of disease.

Methods: We used a decision-analytic model that estimates the incremental cost per quality-adjusted life year (QALY) gained (ICER) from ICU admission compared with general ward care using Norwegian registry data from 2008 to 2010. We assigned increasing weights to health gains for those with higher severity of disease, defined as less expected lifetime health if not admitted. The study has inherent uncertainty of findings because a randomized clinical trial comparing patients admitted or rejected to the ICU has never been performed. Uncertainty is explored in probabilistic sensitivity analysis.

Results: The mean cost-effectiveness of ICU admission versus ward care was €11,600/QALY, with 1.6 QALYs gained and an incremental cost of €18,700 per patient. The probability (p) of cost-effectiveness was 95% at a threshold of €22,000/QALY. The mean ICER for medical admissions was €10,700/QALY (p = 97%), €12,300/QALY (p = 93%) for admissions after acute surgery, and €14,700/QALY (p = 84%) after planned surgery. For individualized ICERs, there was a 50% probability that ICU admission was cost-effective for 85% of the patients at a threshold of €64,000/QALY, leaving 15% of the admissions not cost-effective. In the distributional evaluation, 8% of all patients had distribution-weighted ICERs (higher weights to gains for more severe conditions) above €64,000/QALY. High-severity admissions gained the most, and were more cost-effective.

Conclusions: On average, ICU admission versus general ward care was cost-effective at a threshold of €22,000/QALY (p = 95%). According to the individualized cost-effectiveness information, one in six ICU admissions was not cost-effective at a threshold of €64,000/QALY. Almost half of these admissions that were not cost-effective can be regarded as acceptable when weighted by severity of disease in terms of expected lifetime health. Overall, existing ICU services represent reasonable resource use, but considerable uncertainty becomes evident when disaggregating into individualized results.

Keywords: Cost-effectiveness; Health priorities; Intensive care; Quality-adjusted life years; Resource allocation; Severity of disease.

Fig. 1

Short-term survival benefit of admission to the ICU versus the general ward: assumptions. SAPS II versus risk of death if admitted to the intensive care unit (ICU) or general ward (base case). Multiple grey lines represent the range of modified SAPS II models used in the analysis of uncertainty. For a given SAPS II, the vertical distance between the two lines represents the absolute short-term survival benefit of ICU admission compared to general ward care. For example, a sepsis patient with a predicted hospital mortality of 40% with treatment in the ICU would be attributed an absolute mortality reduction of 42% from admission (indicated by arrow, corresponding relative risk ratio = 0.49). The mountain-like grey shape at the bottom shows the distribution of patients according to SAPS II

Fig. 2

a Cost-effectiveness acceptability curve: all patients. The probability that ICU admission versus general ward care was cost-effective was 95% at a threshold of €22,000/QALY (threshold indicated by long dashed line). b Cost-effectiveness acceptability curve: by type of admission. The probability that ICU admission versus general ward care was cost-effective by type of admission. Threshold of €22,000/QALY indicated by long dashed line. ICER incremental cost-effectiveness ratio, QALY quality-adjusted life year

Fig. 3

a Individualized cost-effectiveness with and without distribution weights for severity of disease: the disaggregated individual results. Each line is made up of 30,712 points. Each point represents the ICER for an individual admission. The individualized ICERs are sorted from the lowest (left) to the highest (right) ICER. There was a 50% probability (median, black line) that ICU admission was cost-effective for 85% of the patients at a threshold of €64,000/QALY (long dashed line). The figure illustrates that after assigning distribution weights according to severity of disease, i.e. higher weights to the health gains of patients with fewer lifetime QALYs if rejected, ICU admission can be considered acceptable for more patients (thick grey line) for any cost-effectiveness threshold compared to the standard analysis (black line). b Individualized cost-effectiveness in subgroups by type of admission. The individualized incremental cost-effectiveness ratios were plotted as points forming a line. The individualized ICERs are sorted from the lowest (left) to the highest (right) ICER. The thick black line is the median result for each individual from 1000 replications of the model. The long dashed line indicates a general cost-effectiveness threshold of €64,000/QALY. ICER incremental cost-effectiveness ratio, QALY quality-adjusted life year