Marieke Krol

Productivity costs in economic evaluations: past, present, future.

Productivity costs occur when the productivity of individuals is affected by illness, treatment, disability or premature death. The objective of this paper was to review past and current developments related to the inclusion, identification, measurement and valuation of productivity costs in economic evaluations. The main debates in the theory and practice of economic evaluations of health technologies described in this review have centred on the questions of whether and how to include productivity costs, especially productivity costs related to paid work. The past few decades have seen important progress in this area. There are important sources of productivity costs other than absenteeism (e.g. presenteeism and multiplier effects in co-workers), but their exact influence on costs remains unclear. Different measurement instruments have been developed over the years, but which instrument provides the most accurate estimates has not been established. Several valuation approaches have been proposed. While empirical research suggests that productivity costs are best included in the cost side of the cost-effectiveness ratio, the jury is still out regarding whether the human capital approach or the friction cost approach is the most appropriate valuation method to do so. Despite the progress and the substantial amount of scientific research, a consensus has not been reached on either the inclusion of productivity costs in economic evaluations or the methods used to produce productivity cost estimates. Such a lack of consensus has likely contributed to ignoring productivity costs in actual economic evaluations and is reflected in variations in national health economic guidelines. Further research is needed to lessen the controversy regarding the estimation of health-related productivity costs. More standardization would increase the comparability and credibility of economic evaluations taking a societal perspective.

Do productivity costs matter?: the impact of including productivity costs on the incremental costs of interventions targeted at depressive disorders.

Background: When guidelines for health economic evaluations prescribe that a societal perspective should be adopted, productivity costs should be included. However, previous research suggests that, in practice, productivity costs are often neglected. This may considerably bias the results of costeffectiveness studies, particularly those regarding treatments targeted at diseases with a high incidence rate in the working population, such as depressive disorders.Objectives: This study aimed to, first, investigate whether economic evaluations of treatments for depressive disorders include productivity costs and, if so, how. Second, to investigate how the inclusion or exclusion of productivity costs affects incremental costs.Methods: A systematic literature review was performed. Included articles were reviewed to determine (i) whether productivity costs had been included and (ii) whether the studies adhered to national health economic guidelines about the inclusion or exclusion of these costs. For those studies that did include productivity costs, we calculated what proportion of total costs were productivity costs. Subsequently, the incremental costs, excluding productivity costs, were calculated and compared with the incremental costs presented in the original article, to analyse the impact of productivity costs on final results. Regression analyses were used to investigate the relationship between the level of productivity costs and the type of depressive disorder, the type of treatment and study characteristics such as time horizon used and productivity cost valuation method.Results: A total of 81 unique economic evaluations of treatments for adults with depressive disorders were identified, 24 of which included productivity costs in the numerator and one in the denominator. Approximately 69% of the economic evaluations ignored productivity costs. Two-thirds of the studies complied with national guidelines regarding the inclusion of productivity costs.For the studies that included productivity costs, these costs reflected an average of 60% of total costs per treatment arm. The inclusion or exclusion of productivity costs substantially affected incremental costs in a number of studies. Regression analyses showed that the level of productivity costs was significantly associated with study characteristics such as average age, the methods of data collection regarding work time lost, the values attached to lost work time, the type of depressive disorder, the type of treatment provided and the level of direct costs.Conclusions: Studies that do not include productivity costs may, in many cases, poorly reflect full societal costs (or savings) of an intervention. Furthermore, when comparing total costs reported in studies that include productivity costs, it should be noted that study characteristics such as the methods used to assess productivity costs may affect their level.

How to estimate productivity costs in economic evaluations

Productivity costs are frequently omitted from economic evaluations, despite their often strong impact on cost-effectiveness outcomes. This neglect may be partly explained by the lack of standardization regarding the methodology of estimating productivity costs. This paper aims to contribute to standardization of productivity cost methodology by offering practical guidance on how to estimate productivity costs in economic evaluations. The paper discusses the identification, measurement and valuation of productivity losses. It is recommended to include not only productivity losses related to absenteeism from and reduced productivity at paid work, but also those related to unpaid work. Hence, it is recommended to use a measurement instrument including questions about both paid and unpaid productivity, such as the iMTA Productivity Cost Questionnaire (iPCQ) or the Valuation of Lost Productivity (VOLP). We indicate how to apply the friction cost and the human capital approach and give practical guidance on deriving final cost estimates.

The iMTA Productivity Cost Questionnaire A Standardized Instrument for Measuring and Valuing Health-Related Productivity Losses

BACKGROUND Productivity losses often contribute significantly to the total costs in economic evaluations adopting a societal perspective. Currently, no consensus exists on the measurement and valuation of productivity losses. OBJECTIVE We aimed to develop a standardized instrument for measuring and valuing productivity losses. METHODS A group of researchers with extensive experience in measuring and valuing productivity losses designed an instrument suitable for self-completion, building on preknowledge and evidence on validity. The instrument was designed to cover all domains of productivity losses, thus allowing quantification and valuation of all productivity losses. A feasibility study was performed to check the questionnaires consistency and intelligibility. RESULTS The iMTA Productivity Cost Questionnaire (iPCQ) includes three modules measuring productivity losses of paid work due to 1) absenteeism and 2) presenteeism and productivity losses related to 3) unpaid work. Questions for measuring absenteeism and presenteeism were derived from existing validated questionnaires. Because validated measures of losses of unpaid work are scarce, the questions of this module were newly developed. To enhance the instruments feasibility, simple language was used. The feasibility study included 195 respondents (response rate 80%) older than 18 years. Seven percent (n = 13) identified problems while filling in the iPCQ, including problems with the questionnaires instructions and routing (n = 6) and wording (n = 2). Five respondents experienced difficulties in estimating the time that would be needed for other people to make up for lost unpaid work. CONCLUSIONS Most modules of the iPCQ are based on validated questions derived from previously available instruments. The instrument is understandable for most of the general public.

Productivity costs in health-state valuations : Does explicit instruction matter?

AbstractBackground: There has been considerable debate on whether productivity costs should be captured in the numerator or the denominator of the cost-effectiveness ratio. That debate cannot be resolved on the basis of theoretical arguments alone because the final choice also depends on what is incorporated in health-state valuations by respondents and how this influences outcomes. At the moment, little is known about whether the effects of ill health on income are included in health-state valuations, and how instructions on including or excluding the effects on income influence health-state valuations. Aim: To conduct an empirical study of health-state valuations to test: (i) whether or not respondents spontaneously include the effect of ill health on income and leisure time; (ii) the impact on the valuation of inclusion (or exclusion) of such effects; and (iii) the influence of explicit instructions on this matter. Methods: Three questionnaires were developed and administered to the general public. Health-state valuations were conducted by visual analogue scale scoring of three health states of differing severity taken from the EQ-5D. Version 1 had no directions regarding inclusion/exclusion of effects of ill health on income. Those respondents who spontaneously included effects on income were subsequently asked to value the same three health states again, excluding these effects. Version 2 had explicit instructions to incorporate the effects on income. Version 3 stated that income was assumed to not change as a result of ill health. Respondents for versions 2 and 3 were also questioned about inclusion of effects on leisure time. Results: Giving explicit instructions on the incorporation or exclusion of effects of ill health on income did not lead to significant differences in subsequent health-state valuations. In the absence of instruction, 36% of respondents included and 64% excluded effects on income, but the health-state valuations of the two groups were not significantly different. Eighty-four percent of respondents included the effects of ill health on leisure activities, and again this had no significant impact on the resulting health-state valuations. Conclusions: It appears that neither spontaneous differences in incorporation of effects on income, nor explicit instructions will yield significantly different health-state valuations. This may suggest that QALY measures are insensitive to concerns regarding effects on income even when these are (explicitly) incorporated, and these effects may therefore be best placed on the cost side of the cost-effectiveness ratio.

In or out? Income losses in health state valuations: A review

BACKGROUND In 1996 the Washington Panel controversially recommended valuing productivity costs (PC) in terms of quality-adjusted life years. The Panels assumption that respondents in health state valuation (HSV) exercises take income losses into account could not be countered since there was no evidence regarding what people consider in HSV exercises. If they do consider income losses and if this changes HSVs, then all economic evaluations that have included PC in the numerator may have double-counted these costs. Alternatively, if respondents do not consider income losses then all past economic evaluations that have not included PC in the numerator have failed to account for sizeable societal costs. OBJECTIVES Through a review we aim to recapture the debate surrounding the appropriate method for including PC in health economic evaluations, to identify empirical evidence addressing the assumptions of the Panel, and recommend a future research agenda. METHODS Through a review we identify, outline, and critically appraise the existing empirical studies that attempt to address whether respondents include income effects in HSV exercises. RESULTS AND CONCLUSION Seven empirical studies were identified. Overall, it seems that not explicitly mentioning the inclusion of income will induce a minority of respondents to include these effects and this appears not to influence results. More empirical work is needed, using generic instruments, larger samples, and using the interview method of administration.

Productivity cost calculations in health economic evaluations: Correcting for compensation mechanisms and multiplier effects

Productivity costs related to paid work are commonly calculated in economic evaluations of health technologies by multiplying the relevant number of work days lost with a wage rate estimate. It has been argued that actual productivity costs may either be lower or higher than current estimates due to compensation mechanisms and/or multiplier effects (related to team dependency and problems with finding good substitutes in cases of absenteeism). Empirical evidence on such mechanisms and their impact on productivity costs is scarce, however. This study aims to increase knowledge on how diminished productivity is compensated within firms. Moreover, it aims to explore how compensation and multiplier effects potentially affect productivity cost estimates. Absenteeism and compensation mechanisms were measured in a randomized trial among Dutch citizens examining the cost-effectiveness of reimbursement for smoking cessation treatment. Multiplier effects were extracted from published literature. Productivity costs were calculated applying the Friction Cost Approach. Regular estimates were subsequently adjusted for (i) compensation during regular working hours, (ii) job dependent multipliers and (iii) both compensation and multiplier effects. A total of 187 respondents included in the trial were useful for inclusion in this study, based on being in paid employment, having experienced absenteeism in the preceding six months and completing the questionnaire on absenteeism and compensation mechanisms. Over half of these respondents stated that their absenteeism was compensated during normal working hours by themselves or colleagues. Only counting productivity costs not compensated in regular working hours reduced the traditional estimate by 57%. Correcting for multiplier effects increased regular estimates by a quarter. Combining both impacts decreased traditional estimates by 29%. To conclude, large amounts of lost production are compensated in normal hours. Productivity costs estimates are strongly influenced by adjustment for compensation mechanisms and multiplier effects. The validity of such adjustments needs further examination, however.

Breaking the Silence: Exploring the Potential Effects of Explicit Instructions on Incorporating Income and Leisure in TTO Exercises

OBJECTIVES An underexplored question in the debate on incorporating productivity costs as costs or effects in a cost-effectiveness (CE) analysis is whether people include effects of ill health on income in health state valuations (HSV). The same holds for the actual inclusion in HSV of the effects of ill health on leisure. This study aims to test whether respondents to HSV using time trade-off (TTO) questions include income and leisure effects without instructions. Moreover, it tests the consequences of explicit instructions to include or exclude income effects. METHODS Three questionnaires were administered among the general public. Respondents were asked to value three distinct EuroQol descriptive system health states using TTO. In version 1, respondents were asked afterwards whether they included income effects. In versions 2 and 3, respondents were instructed upfront to include or exclude income effects. They were furthermore asked whether they included leisure effects. RESULTS A total of 222 respondents completed the questionnaire. In version 1, 64% of the respondents spontaneously included income effects, not resulting in differences in mean valuations. In versions 2 and 3, 88% included leisure time, resulting in a significantly lower TTO value in one health state. With explicit instructions, respondents instructed to include income gave lower HSV for the worst health state presented. CONCLUSIONS Respondents in our sample did not consistently include income effects and leisure effects. Including income effects only had (some) effect on TTO valuations after an explicit instruction. If these results are confirmed in future research, this implies that income effects may be best captured on the cost-side of the CE ratio. Spontaneous inclusion or exclusion of leisure time appeared to be more influential.

A systematic review of economic analyses of pharmaceutical therapies for advanced colorectal cancer.

Colorectal cancer is one of the most common causes of cancer in the Western world. New drugs in the treatment of advanced colorectal cancer, such as irinotecan and oxaliplatin, have substantially increased the cost of treatment. A systematic literature review on the cost (-effectiveness) of pharmaceutical therapies for advanced colorectal cancer was conducted, in which 13 articles were included. The main topics were: orally versus intravenously administered fluoropyrimidine, raltitrexed, irinotecan and oxaliplatin. Additional information was collected on the cost (-effectiveness) of the monoclonal antibodies, cetuximab and bevacizumab. Only five articles had taken the societal perspective, in most articles no data on quality of life was presented, and only two reported the cost per quality-adjusted life year. As only a limited amount of information is available on the cost-effectiveness of pharmaceutical therapies for advanced colorectal cancer, there is a need for more cost-effectiveness studies. These studies are preferably performed by taking a societal perspective and including quality of life outcomes.

The impact of patients' subjective life expectancy on time tradeoff valuations.

Background. Quality-adjusted life-year (QALY) calculations in economic evaluations are typically based on general public or patient health state valuations elicited with the time tradeoff method (TTO). Such health state valuations elicited among the general public have been shown to be affected by respondents’ subjective life expectancy (SLE). This suggests that TTO exercises based on time frames other than SLE may lead to biased estimates. It has not yet been investigated whether SLE also affects patient valuations. Objective. To empirically investigate whether patients’ SLE affects TTO valuations of their current health state. Methods. Patients with different severities of diabetic retinopathy were asked in a telephone interview to value their own health status using TTO. The TTO time frame (t) presented was based on age- and sex-dependent actuarial life expectancy. Patients were then asked to state their SLE. Simple and multiple regression techniques were used to assess the effect of the patients’ SLE on their TTO responses. Results. In total, 145 patients completed the telephone interview. Patients’ TTO values were significantly influenced by their SLE. The TTO value decreased linearly with every additional year of difference between t and the patients’ SLE; that is, patients were more willing to give up years the shorter their SLE compared with t. Conclusion. Patients’ SLE influenced their TTO valuations, suggesting that respondents’ SLE may be the most appropriate time frame to use in TTO exercises in patients. The use of other time periods may bias the TTO valuations, as the respondents may experience the presented time frame as a gain or a loss. The effect seems to be larger in patient valuations than in general public valuations.