A universal outcome measure for headache treatments, care- delivery systems and economic analysis

DOI: https://doi.org/10.1186/s10194- 021- 01269- 9

Abstract-Summary We envisaged a need for a new outcome measure for this purpose, applicable to all forms of treatment, care and care-delivery systems as opposed to comparisons of single-modality treatments.

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We noted that pain was the key burdensome symptom of migraine and episodic tension-type headache (TTH), that pain above a certain level was disabling, that it was difficult to put economic value to pain but relatively easy to do this for time, a casualty of headache leading to lost productivity.

We therefore based the measure on time spent in the ictal state (TIS) of migraine

or TTH, either as total TIS or proportion of all time.

We expressed impact on health, in units of time, as TIS*DW, where DW was the disability weight for the ictal state supplied by the Global Burden of Disease (GBD) studies.

If the time unit was hours, TIS*DW yielded hours lived with (or lost to) disabil-

ity (HLDs), in analogy with GBD’s years lived with disability (YLDs).

Acute treatments would reduce TIS by shortening attack duration, preventative treatments by reducing attack frequency; health-care systems such as structured headache services would have these effects by delivering these treatments.

For health-care systems, additional gains from provider-training (promoting adherence to guidelines and, therefore, enhancing coverage) and consumer- education (improving adherence to care plans), increasing numbers within popula- tions gaining the benefits of treatments, would be measurable by the same metric.

The new outcome measure expressed in intuitive units of time is applicable to treatments of all modalities and to system-level interventions for multiple headache types, with utility for CEA and for informing health policy.

Extended: Our purposes in this manuscript were first to review the literature for candidate measures in common use that might serve the requirements of economic evaluation; second, subject to findings, to develop a new measure applicable equally to all forms of treatment, care and care-delivery systems for headache regardless of type; and third to demonstrate its broad utility in these applications.

Introduction The first manuscript in this themed series noted the high ill-health, disability and economic burdens arising from headache disorders worldwide, which persist despite the existence of effective treatments [387].

Lay a difficulty: on what outcome measure(s) might economic evaluation of headache services, as opposed to single-modality treatments such as acute or pre- ventative drugs, be based?

Previous economic evaluations have used both disease-specific clinical outcomes and generic measures [346, 352, 388–393], but choice among the former has been restricted almost exclusively to those used and reported in randomised clinical trials (RCTs), which are rarely designed to support economic evaluation.

Our purposes in this manuscript were first to review the literature for candidate measures in common use that might serve the requirements of economic evaluation; second, subject to findings, to develop a new measure applicable equally to all forms of treatment, care and care-delivery systems for headache regardless of type; and third to demonstrate its broad utility in these applications.

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Review of Potential Candidate Measures We limited it to efficacy measures previously employed in assessing treatments of migraine and/or tension-type headache (TTH), these being the principal headache disorders for which headache services cater [387].

Pain-freedom may be the outcome most desired by people treating either disor- der, and the IHS guidelines for clinical trials in migraine recommend PF2 as pri- mary efficacy endpoint [394].

While use of rescue medication is a measure reflecting primary inefficacy, and expresses an important dimension of outcome, it is applicable only to subsets expe- riencing this: in the trials, about 60% taking ASA for migraine and 85% for TTH did not require rescue.

A disability-based outcome measure could serve all purposes: comparative eval- uation of headache treatments of all types, effectiveness assessment of care-delivery systems, and economic analysis.

Development of a New Measure Acute treatments would diminish (avert) HLDs by shortening attack duration, pre- ventative treatments by reducing attack frequency; health-care systems such as structured headache services [387] would have these effects or would supplement them by delivering or enhancing delivery of these treatments.

Population estimates would involve interpreting SHR24 reports from RCTs (for example [395–397]): acute drugs would reduce pain intensity from disabling levels to non-disabling within 2 h, without recurrence, in the proportion of attacks stipu- lated by SHR24 as a reported outcome measure.

For multiple attacks over time, HLDs averted would be dtTIS*DW, with the assumption that treatment was taken before or as soon as headache became dis- abling so that there was no measurable health loss before treatment.

It would not satisfactorily account for serious AEs, which always require sepa- rate recording.) For preventative treatments, effects would be expressed in HLDs averted through the same product dtTIS*DW, again reducible, should the purpose require it, by the proportion of treatment discontinuations due to AEs.

Discussion This presentation has described the conception and delineation of a new universal outcome measure applicable to treatments of all modalities of headache of multiple types (migraine or TTH, but also of other types manifesting as attacks definable in terms of duration and frequency) and expressed in intuitive units of time.

Multiple outcome measures existed already for treatments of migraine and TTH, and several were widely accepted, though not, perhaps, with universal agreement [398, 399].

In the context of economic analysis, with the purpose of valuing interventions of different types relative to each other, existing measures were applied with difficulty. A second, that acute treatment is initiated before or as soon as pain becomes disabling, is an assumption necessary to establish a time zero for purposes of effect calculation.

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Because it discounts mild pain, the measure has a more restricted application to TTH than to migraine: TTH is, usually but not always, a mild-to-moderate head- ache [400].

Conclusions We have described the development of a new universal outcome measure expressed in intuitive units of time and applicable to treatments of all modalities of headache of multiple types.

The measure equips economic analysis of interventions, including implementa- tion of structured headache services, for purposes including informing health policy.

Acknowledgement A machine generated summary based on the work of Steiner, Timothy J; Linde, Mattias; Schnell-Inderst, Petra. 2021 in The Journal of Headache and Pain.

Validation of a self-reported instrument to assess work-related difficulties in patients with migraine: the HEADWORK questionnaire