[The indirect costs of tension type headache. A systematic literature review].

Objective: The objective of this work was to systematically review the published literature in relation to the estimated indirect costs associated with TTH.

Design: This systematic review followed the Preferred Reporting Items Statement for Systematic Reviews and Meta-analyzes (PRISMA).

Data Sources: The review was performed in two main databases, PubMed and EconLit, and was completed with the gray literature search.

Study Selection: The basic criterion for the inclusion of studies was that they present at least one measure of indirect costs specific to TTH.

Data Extraction: 12 studies were finally selected for information extraction. Of all the selected articles, the characteristics of the study design, the types of costs included, as well as the measurement instrument, and the main results were synthesized.

Results: The search yielded a total of 568 studies. Heterogeneity was found in the designs and samples/populations of the included studies. Only two studies estimated direct and indirect costs for TTH. Among the most notable results, we find an estimated moderate impact of disability due to TTH (between 0.037 and 0.15 per person, 0.06-0.09% for the population). Productivity and efficiency losses were observed and were very heterogeneous. The willingness to pay for effective treatment would range from $1.32 to $9.20 per month. Quality of life is low, between 28.2 and 28.4 points out of 100, and health-related quality of life seems to improve significantly with treatment.

Conclusions: Despite the high heterogeneity of the results, we can conclude that tension headache is characterized by a moderate impact on disability, on productivity and efficiency at work or school, and on the quality of life of those who suffer it.