Abstract
OBJECTIVE: To assess the acceptability and validity of a patient-reported cost diary to estimate health resource utilization (HRU) and costs associated with deep vein thrombosis (DVT) and post-thrombotic syndrome (PTS).
METHODS: We developed a cost diary for use in the Venous Thrombosis Outcomes (VETO) Study, a prospective multicenter cohort study of long-term outcomes after DVT. The VETO cost diary is a 28-item patient-reported questionnaire used to capture information pertaining to HRU and direct and indirect costs attributable to DVT and PTS. Data for HRU and direct costs included hospitalizations, physician visits, purchase of prescription and over-the-counter medications, use of transportation and other medical services and purchase or rental of equipment. Data pertaining to indirect costs included time lost from work by patients or their caregivers. Patients were asked to complete the cost diary monthly for 1 year, then for 3 randomly chosen months for the 2nd year. Acceptability of the cost diary was assessed by estimating the percent of time coverage per patient over the study follow-up period. Internal consistency was assessed by comparing data reported by patients in the cost diary to similar data collected in nurse-administered study questionnaires. External validity was assessed by comparing HRU data reported in the cost diaries to patient-specific data obtained from the administrative database of the Province of Quebec Health Insurance Board (RAMQ) for the same time period.
RESULTS: 387 patients with objectively diagnosed DVT participated in the VETO Study, of whom 359 from 7 hospitals in Quebec, Canada contributed to this analysis (∼ 40% developed PTS). Analyses showed that acceptability of the cost diary was high, with more than 82% of patients reporting data for > 90% of the study follow-up period. Internal consistency analyses revealed discrepancies in reporting of hospitalizations in cost diaries compared to nurse-administered questionnaires (144 vs. 97 hospitalizations, respectively, reported in the first year of the study). Analyses of external validity showed that for the first 4-month study period, the mean number of DVT-related prescriptions reported in the cost diary was comparable to that reported in the RAMQ database (2.48 vs. 3.84, respectively), as was the mean number of DVT-related medical visits (6.39 vs. 7.18, respectively).
CONCLUSION: Overall, the VETO cost diary appears to be an acceptable and valid patient-reported instrument that can be used to estimate HRU, direct and indirect costs attributable to DVT and PTS. Further analyses are needed to identify the factors affecting the internal consistency of the cost diary.
