Fig. 18.1
Different types of economic analyses
Users of HE literature in epilepsy can benefit from a systematic approach to critically appraise the validity and applicability of EAs by applying a simple 9-item checklist (Table 18.1) [6]. The viewpoint of the study determines the range of costs and consequences included in an EA, and can be that of the patients, the health care institution, the insurer or health system, and society as a whole. A broad societal perspective, which incorporates the patient’s productivity and ability to work, is often recommended. Because subgroups of patients can have vastly different costs and outcomes, these should be adequately explored and reported. Many issues influence cost measurement and valuation; authors should report the physical quantities of resources used, which allows readers to extrapolate results from one setting to another, and they should distinguish between charges and real costs. The types of costs included in the EA determine its scope. A narrow perspective includes only direct costs (i.e., costs directly attributable to epilepsy and its treatment), which can be medical and nonmedical (transportation, home support, etc.). A broader perspective includes also indirect costs (e.g., productivity costs) and intangible costs (e.g., the value of pain and suffering), although the latter are difficult to quantify monetarily. Of particular relevance in long-term EAs is accounting for the lower value of costs or outcomes incurred in the future. This is usually addressed by discounting future events at a rate of 3–5 % to approximate future to present values. In the absence of long-term medical and surgical epilepsy cohorts or randomized trials, long-term EAs resort to models (such as decision analysis and Markov models-Stochastic model to study health outcomes using health states and health transitions iteratively) in which future costs and outcomes are predicted based on assumptions that should be clearly stated and subjected to sensitivity analyses to assess their robustness. Sensitivity analysis refers to repeating the evaluation using a range of plausible probabilities of outcomes, costs, and value judgments to assess whether the results change substantially. In interpreting the results of EAs, clinicians should look for incremental analyses based on a ratio of the difference between alternatives in costs and outcomes, and often expressed as an Incremental Cost-Effectiveness Ratio (ICER):
![$$ ICER=\frac{\left[{C}_A-{C}_B\right]}{\left[{O}_A-{O}_B\right]}, $$](https://i0.wp.com/neupsykey.com/wp-content/uploads/2017/06/A318697_1_En_18_Chapter_Equa.gif?w=960)
where C A and C B are the costs of alternatives A and B, and O A and O B are the outcomes of alternatives A and B. Costs are usually expressed in monetary units, benefits are expressed in clinical units (seizure freedom) or more often in QALYs, and the ICER is often expressed as Cost per QALY.
Table 18.1
Checklist to assess the validity and applicability of economic evaluations
Are the results valid? |
1. Did the investigators adopt a sufficiently broad viewpoint (patients, treatment options, and outcomes)? |
2. Are the results reported separately for relevant patient subgroups? |
3. Were costs measured accurately? |
4. Did investigators consider the timing of costs and consequences? |
What are the results? |
5. What are the incremental costs and effects of each strategy? |
6. Do incremental costs and effects differ between groups? |
7. Was a sensitivity analysis performed to assess impact of different cost assumptions? |
Can I apply the results to patient care? |
8. Are the treatment benefits worth the risks and costs (including patient values)? |
9. Can I expect similar costs in my setting? |
A final point pertains to what constitutes a cost-effective intervention, that is, the ICER that warrants adoption of an intervention by a health system. Although more relevant to policy makers than to individual clinicians, this is important to consider given the increasing pressure on clinicians for “bedside allocation” (see above). The World Health Organization’s (WHO) CHOICE project has published threshold values for intervention cost-effectiveness in the different world regions based on their gross domestic product (GDP) expressed in 2005 International dollars, and adopting quality adjusted life years (QALYs) as the outcome [7]. The cost-effectiveness of interventions is divided into three categories: (1) very cost-effective if the cost per QALY (ICER) is less than the region’s GDP per capita, (2) cost-effective if it is between 1 and 3 times the GDP per capita, and (3) not cost-effective if it is >3 times the GDP per capita. The upper threshold for cost-effective interventions ranges from Int$ 5,086 in the poorest African countries, to Int$ 119,849 in affluent North American countries (Fig. 18.2).
Fig. 18.2
WHO cost-effectiveness thresholds for interventions, expressed as Cost (2005 international $) per QALY Footnote: GDP gross domestic product; < GDP per capita (very cost-effective); 1–3 × GDP per capita (cost-effective); > 3 × GDP per capita (not cost-effective). Afro African region, Amro American region, Emro European region, Euro European region, Searo South East Asia region, Wpro Western Pacific region. Suffixes A to E after each region indicate gradation of population health indicators in terms of adult and infant mortality, A = best, E = worst
The Cost of Epilepsy
Studies of COI in epilepsy are challenging. First, COI studies incorporating measures of direct, indirect, and intangible costs are rare. Most studies focus primarily on direct costs and even when indirect and intangible costs are incorporated, the components included vary among studies. Second, COI studies span a variety of time horizons, geographic regions (health care costs differ substantially between countries) and populations, making comparisons between studies impossible in the absence of reports of physical units of resources used. Finally, most long-term COI studies of epilepsy (i.e., lifetime costs of incidence cohorts) usually provide estimates based on modeling, because prospective studies with rigorous and comprehensive data collection are sparse. Studies consistently show that antiseizure medications and hospital admissions have become the largest component of direct costs (median 31 % and 34 %, respectively) [5], particularly in those with difficult-to-treat or newly diagnosed epilepsies [8, 9]. Cost estimates vary markedly among studies, as demonstrated in a review of population-based prevalence studies, where the annual per-patient direct costs of epilepsy in Italy and the UK (5 studies) ranged from $803 (USD) to $3,208 (USD) in those with active epilepsy, and it ranged from $126 (USD) to $1,748 (USD) in those with inactive epilepsy [8]. A more recent review also found that the annual direct per-patient costs of prevalent epilepsy in 15 international studies ranged from $55 (USD) in India to $3,065 (USD) in the UK [5].
Although costs of epilepsy vary among studies, direct costs are always higher in the first year after diagnosis (up to four times higher than in subsequent years) [5, 8]. In a systematic review of 22 COI studies in epilepsy worldwide (most from Europe and the USA but also from India, Hong Kong, Oman, Burundi, Chile, and Mexico), every study used a bottom-up approach (using individual patient records) and most only measured direct costs [9]. Antiseizure medications were the main contributor to direct costs, while indirect costs ranged between 12 and 85 % of the total annual costs in the 12 studies that estimated these. Unfortunately, results of bottom-up approach COI studies, although more precise, may not be applicable to population-based cohorts of persons with epilepsy. A systematic review examining predictors of cost and health resource utilization in epilepsy in five studies [10] found no association between demographic factors studied and costs or health resource utilization, while increased seizure frequency and severity along with polytherapy or higher number of AEDs predicted costs.
Epilepsy Surgery Is a Cost-Effective Intervention
In this section, we review long-term EAs of epilepsy surgery, which were identified by searching Embase and Medline on August 1, 2014, using the following strategy: epilepsy AND (economic* or cost or quality-adjusted life years or QALY) AND (surgery or amygdalo-hippocampectomy or amygdalo-hippocampectomy or resection or callosotomy or hemispherectomy or lesionectomy or transection or vagus nerve stimulation or hippocampal stimulation or deep brain stimulation or gamma knife surgery or ablation or subpial transsection). We included studies that examined long-term (5 years or longer) costs and outcomes of epilepsy surgery, and compared epilepsy surgery to another intervention (e.g., medical management). Review articles on the cost of epilepsy and included articles were also hand searched.
Ten articles published between 1995 and 2014 met eligibility criteria (see Appendix) [11–20]. Studies were performed in Canada (n = 3), the USA (n = 3), the UK (n = 2), France (n = 1), and India (n = 1). All long-term analyses relied on modeling because there are no actual long-term data. There were only two pediatric studies [11, 14], no studies focused on the elderly, and none addressed palliative surgeries or electrical stimulation aside from two studies examining the cost-effectiveness of vagus nerve stimulation, one of which was a follow-up of the other [12, 13]. Most studies had a health system or insurer viewpoint. Only three studies adopted a societal perspective [15, 17, 19] (although one assumed no productivity changes [15]), and only one study (from France) included intangible costs [19]. All but one study derived long-term estimates of surgical and medical costs from decision analysis modeling [18]. Half of the studies were cost-effectiveness analyses with seizure control as the outcome of interest [14, 17–20], and half were cost-utility analyses [11–13, 15, 16] that calculated QALYs using utility weights derived from the literature, from direct measurement, or by extrapolating from quality of life (not utility) scores. The cost, outcomes, and long-term data sources to generate the models included bottom-up local data, expert opinion, patient surveys, and published studies. Temporal lobe resection was overwhelmingly the commonest surgical procedure considered. Nearly every study used sensitivity analyses, but the variables and results were heterogeneous. Methodological quality was generally poor and the scope tended to be narrow, although more recent studies dealing with resective surgery had substantially improved quality and reporting [11, 19].
Results were reported in a nonstandardized and highly variable manner. In general, seizure freedom was an important factor associated with lower costs after surgery. Every study demonstrated that, in the base model and also in many sensitivity analyses, epilepsy surgery was more effective than medical therapy in the long term (i.e., yielded more QALYs), and it became less costly over time (i.e., surgery dominated medical care). Costs per QALYs for epilepsy surgery were within acceptable ranges when compared to other common interventions and/or treatments [15, 16]. In the USA, the ICER was $15,581 [16] considering only direct costs, and $27,200 considering direct and indirect costs (but assuming no change in productivity). Both of these are below the USA GDP per capita ($40,000) and well within the “very cost-effective” range suggested by WHO thresholds [7]. In general, epilepsy surgery became cheaper than medical therapy anywhere from 7 to 14.4 years after surgery in the base case models, although direct costs dropped rapidly immediately after surgery in seizure-free patients.
Related posts:
Long-Term Cognitive Outcomes After Epilepsy Surgery in Children
Long-Term Psychiatric Outcomes After Epilepsy Surgery in Adults
Long-Term Educational and Vocational Outcomes of Adults After Epilepsy Surgery
Quality-of-Life Outcomes in Adults Following Epilepsy Surgery
Subjective Experiences of Children and Parents After Epilepsy Surgery
Managing Expectations of Epilepsy Surgery
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