From: Cost-effectiveness analysis of interventions for migraine in four low- and middle-income countries
 | Assumption | Justification | Impact or weight in the model |
---|---|---|---|
1 | Mild headache is not associated with disability | If the assumption were false, the cost-effectiveness of acute therapy would be slightly reduced | |
2 | The pain associated with untreated migraine is at least moderate | On the one hand, the diagnostic criteria for migraine describe the pain as at least moderate [11]; on the other hand, most clinical trials have recruited patients with at least moderate pain | None |
3 | In a stepped-care treatment paradigm, triptans are used only by non-responders to simple analgesics | This is the standard stepped-care paradigm, in which more expensive medications are reserved for those shown to need them | The alternative would be a multiplicity of scenarios of no obvious interest |
4 | Acute treatment is initiated at attack onset (commencement of pain phase) | The assumption was necessary to establish a time zero for purposes of effect calculation and was subject to further assumptions regarding patient adherence (see below) | To the extent that the assumption was false, effect and therefore cost-effectiveness would be reduced |
5 | Each acute medication is used once per attack | The assumption was necessary because of dependence on clinical trials data | Additional doses would increase cost, particularly in the case of triptans (mean number of triptan doses per attack was reported as 1.4-1.5 in the USA [12], but this may not be representative of the countries of interest) |
6 | The endpoint of sustained headache-relief is an all-or-nothing response | The assumption is in line with the standard definitions of pain relief and sustained pain freedom [13] | The consequence of the assumption was an underestimation of effectiveness |
7 | Prophylaxis is offered only to the proportion of people with ≥3 migraine attacks/month | As a recommendation based on frequency only, this was conservatively chosen [6] | This is a clinical rather than an economic threshold, so it would be of limited interest to vary it. Lowering the threshold to ≥2 would increase the use of prophylactics with less gain per user |
8 | ASA has high current coverage (80%) in all study contexts except Zambia (50%) | This was conservative; ASA is available almost universally, but not easily in rural Zambia | No impact on cost-effectiveness estimations. Higher coverage would allow greater population health gain |
9 | As a result of non-adherence, a proportion of patients use OTC-drugs later than is ideal, and in suboptimal doses (described in the text). | Best estimate, formed from our clinical judgement | Better adherence would lead to higher health gain and therefore improve cost-effectiveness |
10 | Provider adherence is 75% | Best estimate, based on our experience | Higher adherence would allow greater population health gain, which would improve cost-effectiveness estimations |
11 | Public education improves adherence by 50% of the current deficit | Based on what can be in expected in real world settings | A greater improvement of consumer adherence would lead to improved cost-effectiveness as well as greater population health gain |
12 | Three-monthly doctor visits, each of 10 minutes’ duration, are needed for monitoring and prescription of triptans and prophylactics | Reflects typical clinical need and treatment practice in these countries | More or longer visits would increase costs |
13 | For consumer education, the number of leaflets needed is 50% of the disease prevalence, and one poster is required per 2,000 of the population | Leaflet numbers allows for high circulation/exposure; poster numbers conform to WHO programme costing standards | Increasing or decreasing leaflet or poster numbers would have a negligible impact on base-line results because the base-line cost of consumer education is very low (US$ 0.01-0.02 per capita) |
14 | For provider education, one physician per primary health-care centre per year will be trained for one day | This represents an effective approach to reaching primary health care throughout the country | Increasing or decreasing the number of trained providers would have a negligible impact on base-line results because the base-line cost of provider education is very low (US$ 0.01-0.02 per capita) |