Objective. To render information on the accuracy of patient-reported indirect cost data compared with payer-derived data of the real indirect costs on a patient-by-patient basis concerning disease-related productivity losses in rheumatoid arthritis (RA). Methods. The assessment of indirect cost data was part of a clinical, multicenter, randomized RA trial. A total of 234 patients of working age with a diagnosis of RA (according to 1987 American College of Rheumatology criteria) were recruited. Demographics of the cohort were mean age 53 years, mean disease duration 8 years, 76% were women, and all had membership in the regional statutory health insurance plan. Every 3 months corresponding indirect cost data were derived for the cohort from a health economic questionnaire for cost assessment in patients with RA and the payer's database over a period of 18 months. Comparative statistical analyses were performed between patient-reported and insurance claims data. Results. The mean annual productivity losses due to sick leave amounted to 14 and 17 days per patient (questionnaire versus payer data), and productivity losses due to work disability amounted to 3 days (both); monetary valuation renders overall costs of €1,240 and €1,590, respectively. The difference of 17% in overall productivity losses is not significant. Comparison of productivity losses reveals a strong correlation of r ‫؍‬ 0.83 in those due to sick leave and of ‫؍‬ 0.84 in those due to work disability between questionnaire and payer data. Conclusion. The comparison of questionnaire and payer data shows that RA patients report their productivity losses adequately. Indirect cost assessment should therefore be included in further RA trials and observational studies.

Objective.To investigate the level of detail required in self-reported health care utilization questionnaires for administration to patients with rheumatoid arthritis (RA). Methods. A preliminary questionnaire was developed on the basis of existing tools for use in rheumatic conditions and in-depth interviews with 10 RA patients. Data gathered over 1 year of administration in a clinical setting were then matched to a comprehensive database of payer-reported information. Kappa statistics were calculated for each health care utilization domain. For domains where disaggregation into metric data was potentially preferable, histograms of difference were assessed visually and the strength of association examined using Spearman's rank correlation coefficient. ‫؍‬ 0.13) and amount (r ‫؍‬ 0.39, P < 0.001). Conclusion. The use of highly aggregated items to assess health care utilization in RA is supported. Dichotomous assessment (yes/no) was the preferred level of detail for items in the domains covering medication and diagnostic procedures or tests. Metric data is appropriate in 3 areas: number of physician visits, number of inpatient days, and total expenditure on transportation.

We present a matrix of relevant resource utilization domains for use in standardizing applied cost assessment in musculoskeletal conditions. In addition,we highlight the importance of selecting cost categories during the development of an economic evaluation. A set of four steps was applied: (a) literature search identifying economic evaluations in osteoarthritis and osteoporosis, (b) listing and aggregation of cost categories mentioned in the identified articles, (c) development of a matrix of resource utilization domains, and (d) qualitative discussion regarding the generalizability of the matrix to other musculoskeletal conditions such as rheumatoid arthritis. We examined 41 full-length articles (25 cost-of-illness studies or cost-comparisons, 14 cost-effectiveness analyses, and 2 cost-utility analyses), of which 16 studies focused on osteoarthritis and 25 on osteoporosis. The reviewed studies used a total of 151 different cost categories which, after adjustment for synonymous labeling, made up 34 cost categories. A matrix of 16 separate resource utilization domains was developed including seven outpatient, three inpatient, four other disease-related, and two productivity cost domains. We found that cost assessment in economic evaluation in the key musculo-skeletal diseases (osteoarthritis, osteoporosis, and rheumatoid arthritis) is performed rather inhomogeneously. A generalized matrix of applicable resource utilization domains and a flowchart facilitating the development of appropriate resource utilization data have been developed.

Interventions such as reduction in disease progression and control of disease activity, early vocational rehabilitation measures and vocational retraining in patients at risk of quitting working life, and self-management programs to learn coping strategies might decrease future RA-related productivity costs.