Direct comparison
Human Capital vs. Friction Cost
How the human capital and friction cost methods value lost productivity differently, and which HTA guideline bodies require each.
Written and maintained by CASRAI Editorial Board
Last updated
Ask CASRAI · included with Regulatory Radar
Ask about Human Capital vs. Friction Cost
Ask CASRAI answers research-administration questions and cites the passages behind every claim — and says so when the corpus does not cover something, instead of guessing. It comes with a Regulatory Radar subscription at $29 a month, alongside the daily digest of regulatory changes and the dashboard of what changed.
150 questions a day, on this site, over the API, or inside your own tools through the CASRAI MCP server.
Everything CASRAI publishes — this page, the dictionary, the guides and the news — stays free to read, with no account and no card.
How do Human Capital Approach, Friction Cost Approach compare side by side?
The table below compares Human Capital Approach, Friction Cost Approach across 11 procurement-relevant dimensions, from what it values through best used when.
Side-by-side comparison
| Dimension | Human Capital Approach | Friction Cost Approach |
|---|---|---|
| What it values | The full value of every hour of work the patient would have produced had they stayed healthy, at the market wage (sometimes including fringe benefits), for the whole absence period — and, for a fatal or permanently disabling condition, projected out to normal retirement age. | Only the output actually lost to the economy during the 'friction period' — the time an employer needs to restore production to its pre-absence level, usually by filling the post from unemployment or job-to-job mobility. Once that period ends, further absence is treated as having no net productivity cost to society, because the position has been backfilled. |
| Underlying labor-market assumption | Full employment / a frictionless labor market — no one is readily available to step into the vacated role, so every lost hour is an hour of output the economy permanently forgoes. | Structural unemployment and worker mobility — most positions can be refilled within weeks to a few months, so the real societal loss is bounded by that replacement lag rather than by the worker's remaining career. |
| Origin | Rooted in 1960s human-capital theory in labor economics and carried into cost-of-illness accounting from Dorothy Rice's foundational U.S. cost-of-illness work of the 1960s onward. | Introduced explicitly as an alternative to the human capital method by Koopmanschap, Rutten, van Ineveld and van Roijen, “The friction cost method for measuring indirect costs of disease,” Journal of Health Economics, 1995, from the Institute for Medical Technology Assessment (iMTA), Erasmus University Rotterdam. |
| Typical size of the estimate | Substantially larger, especially for long-term absence, permanent disability, or premature death in a working-age patient — it counts years of forgone wages that FCA treats as absorbed by a replacement worker. | Substantially smaller for the same case, because the costed period is capped at the friction period instead of extending to retirement or life expectancy. |
| What it requires to calculate | Wage data (sometimes including employer non-wage labor costs) and, for chronic or fatal cases, a work-life-expectancy or retirement-age assumption, often discounted to present value. | Wage data plus an empirically estimated friction period, usually derived from national labor-force or job-vacancy-duration statistics, and an assumption about how completely production is lost during that period. |
| Guideline bodies that favor it | Still common in published cost-of-illness literature and widely used in U.S. analyses; the Second Panel on Cost-Effectiveness in Health and Medicine's 2016 recommendations discuss productivity costs within a broader societal-perspective 'impact inventory' without mandating the friction cost method. | Required as the base-case method by the Dutch guideline for economic evaluations in healthcare (Zorginstituut Nederland's costing guideline), and treated favorably in several European HTA methods documents as the more defensible estimate of society's true opportunity cost. |
| Where NICE's reference case fits | Outside NICE's reference case entirely — NICE's base-case perspective is NHS/Personal Social Services, which excludes productivity costs altogether, so this specific choice doesn't arise in the base-case ICER. | Same exclusion applies. If a supplementary societal-perspective analysis is presented alongside the NICE reference case, HCA vs. FCA still has to be chosen for that supplementary estimate, and good-practice guidance favors disclosing which was used and why. |
| Effect on study conclusions | Can make an intervention that averts long-term absence or premature death look strongly cost-saving, or even net cost-saving overall, once avoided productivity loss is added to the ledger — sometimes dominating the direct medical-cost side of the analysis. | Shrinks the productivity offset substantially, which can turn an intervention that looked cost-saving under HCA into one that is merely cost-effective, or not cost-effective, once productivity gains are capped at the friction period — same clinical evidence, a different policy conclusion. |
| Scope: absenteeism vs. presenteeism | Classically applied to absenteeism (time completely missed from work) and to premature mortality; extending it to presenteeism (reduced output while still at work, e.g. from fatigue or pain) multiplies the same full-wage logic across every affected hour on the job, which can inflate estimates further if not handled carefully. | Also classically an absenteeism method — the friction-period logic assumes a vacancy to fill, which doesn't apply cleanly to presenteeism. Studies that want to cost presenteeism alongside a friction-cost absenteeism estimate generally value it separately, often using a validated instrument like the Work Productivity and Activity Impairment (WPAI) questionnaire, rather than folding it into the friction-cost calculation itself. |
| How ISPOR-style good practice treats the choice | ISPOR task force guidance on productivity-cost measurement does not mandate the human capital approach, but recognizes it as the more established method in much of the literature and an acceptable choice when it matches the target jurisdiction's convention or is being used deliberately as an upper-bound estimate. | The same guidance treats the friction cost method as the more theoretically defensible estimate of the true opportunity cost to society under realistic labor-market conditions, while noting practical challenges: friction-period length and the completeness of production loss within it are themselves estimated parameters, so results are sensitive to those assumptions. |
| Best used when | A funder's brief or a jurisdiction's guideline specifically calls for it, or it is reported as an upper-bound sensitivity-analysis figure alongside a friction-cost base case, consistent with CHEERS 2022 reporting norms for transparency on methodological choices. | The analysis targets a jurisdiction or audience that treats it as the methodologically preferred base case (the Netherlands is the clearest example), or whenever a more labor-market-realistic, conservative productivity-cost estimate is wanted. |
Common questions
Common questions about Human Capital Approach vs Friction Cost Approach
What is the human capital approach in a cost-of-illness study?
+
It values a patient's lost productive time at the full market wage for the entire period they cannot work — through the acute illness, any long-term disability, or, for a fatal condition, all the way to the normal retirement age. It treats every lost work-hour as a permanent loss to the economy, because it assumes no one else is readily available to do that work instead.
What is the friction cost approach and why does it produce lower estimates?
+
The friction cost approach, developed by Koopmanschap and colleagues in 1995, argues that in a real labor market with unemployment and job mobility, an employer typically refills an absent worker's post within a bounded 'friction period.' Because production is restored once the replacement is in place, the approach counts only the output lost during that friction period rather than the worker's entire remaining working life — which is why its estimates run far below the human capital approach for the same clinical case, particularly for long-term absence or premature death.
Which approach do health-economic guideline bodies recommend?
+
There is no single global standard. The Dutch guideline for economic evaluations in healthcare (Zorginstituut Nederland) requires the friction cost method as the base case. NICE's UK reference case sidesteps the question by excluding productivity costs from its NHS/PSS-perspective base case entirely. U.S. guidance from the Second Panel on Cost-Effectiveness in Health and Medicine discusses productivity costs as part of a societal-perspective impact inventory without mandating either method, and the human capital approach remains common in the published literature. Always follow the specific guideline your target journal, funder, or HTA body requires.
Can a study report both approaches?
+
Yes, and it is often good practice to do so. A common design is to run the friction cost approach (or whichever method the target jurisdiction's base case requires) as the primary analysis, then present the human capital approach as an upper-bound sensitivity analysis — making the sensitivity of the conclusion to this single methodological choice explicit, which is consistent with CHEERS 2022's emphasis on transparent reporting of costing methods and assumptions.
Does the choice between them affect cost-effectiveness conclusions, or only cost-of-illness totals?
+
Both. In a cost-of-illness study it changes the headline national or per-patient cost burden directly. In a cost-effectiveness or cost-benefit analysis taken from a societal perspective, it changes how large the productivity-cost offset is on one side of the ledger — which can be large enough, for interventions that prevent long absences or premature death in working-age patients, to shift a study's conclusion from 'cost-saving' to merely 'cost-effective,' or to change which of two competing interventions comes out ahead.
Going deeper
