Estimating informal care effects associated with EQ-5D tariff values for use in economic evaluation

This report presents the findings of a study that estimates informal care need using the health of the patient measured by EQ-5D, ICD chapter and other health and sociodemographic data. The results can be used to predict changes in informal care associated with changes in the health of the patient measured using EQ-5D.

Methods

Data was used from a prospective survey of inpatients and contained 59,512 complete responses across 44,494 individuals. The number of days a friend or relative has needed to provide care or help with normal activities in the last six weeks was estimated using the health of the patient measured by EQ-5D, ICD chapter and other health and sociodemographic data. A variety of different regression models were estimated that are appropriate for the distribution of the informal care dependent variable, which had large spikes at 0 (zero informal care) and 42 days (informal care every day).

Results

The preferred model that most accurately predicted the distribution of the data was the zero-inflated negative binomial with variable inflation. The results indicated that improving the health of the patient reduces informal care need. Patients with comorbidities had greater informal care need. The relationship between ICD chapter and informal care need was not as clear.

Discussion

The preferred zero-inflated negative binomial with variable inflation model can be used to predict changes in informal care associated with changes in the health of the patient measured using EQ-5D, and these results can be applied to existing datasets to inform economic evaluation. Limitations included recall bias and response bias of the informal care data, and restrictions of the dataset to exclude some patient groups.