[Cost evaluation by a patient questionnaire: pilot study of a weekly cost diary]

Weekly cost diaries are instruments to measure direct and indirect costs prospectively by using patient data. First we searched MEDLINE for information concerning the use of diaries in health care and their methodological evaluation. Based on a Dutch weekly cost diary we developed an instrument for patients with acute or chronic back pain to be completed following participation in an inpatient rehabilitation measure. Its use was tested in an explorative pilot study. We asked for all costs and resource use due to back pain (all direct medical and non medical costs as well as indirect costs) occurring in a 4-week follow-up period, irrespective of the cost carrier. The total response rate was 58%. Patients spent an average 13 minutes a week for completing the questionnaire, without reporting any major methodological difficulties. Some 30% percent of overall costs were direct costs, the majority being non-recurring costs for assistive devices such as mattresses and mattress frames. Excluding these, monthly direct costs per patient were 270 DM on average. Indirect costs, mainly due to absence from salaried work, amounted to an average 1634 DM per patient, with marked variation. Our study results show that this instrument is basically useful and feasible in this indication. Further studies with larger and representative samples are needed to evaluate data quality. It is suggested that weekly cost diaries can be useful tools in particular in decentralized health care systems to measure costs from the societal perspective.