Healthcare costs of asthma comorbidities: a systematic review protocol.

IntroductionAsthma is associated with many comorbid conditions that have the potential to impact on its management, control and outcomes. These comorbid conditions have the potential to impact on healthcare expenditure. We plan to undertake a systematic review to synthesise the evidence on the healthcare costs associated with asthma comorbidity.Methods and analysisWe will systematically search the following electronic databases between January 2000 and January 2017: National Health Service (NHS) Economic Evaluation Database, Google Scholar, Allied and Complementary Medicine Database (AMED), Global Health, PsychINFO, Medline, Embase, Institute for Scientific Information Web of Science and Cumulative Index to Nursing and Allied Health Literature. We will search the references in the identified studies for additional potential papers. Additional literature will be identified by contacting experts in the field and through searching of registers of ongoing studies. The review will include cost-effectiveness and economic modelling/evaluation studies and analytical observational epidemiology studies that have investigated the healthcare costs of asthma comorbidity. Two reviewers will independently screen studies and extract relevant data from included studies. Methodological quality of epidemiological studies will be assessed using the Effective Public Health Practice Project tool, while that of economic evaluation studies will be assessed using the Drummond checklist. This protocol has been published in International Prospective Register of Systematic Reviews (PROSPERO) database (No. CRD42016051005).Ethics and disseminationAs there are no primary data collected, formal NHS ethical review is not necessary. The findings of this systematic review will be disseminated in a peer-reviewed journal and presented at relevant conferences.Prosperoregistration numberCRD42016051005.