Validity of the Health Belief Model Applied to Influenza among people with chronic diseases: Is it time to develop a new knowledge domain?

There is a lack of comprehensive instruments for the assessment of compliance with influenza immunization. The purpose of this study was to examine psychometric characteristics of the Health Belief Model Applied to Influenza (HBMAI) among people with chronic diseases. We selected people residing in four municipalities of the Foča region (Republic of Srpska-Bosnia and Herzegovina) who were listed in the official records to receive the recommended influenza immunization in 2017/2018. Participants were interviewed using the HBMAI questionnaire at their homes. The HBMAI is composed of 45 items classified in 7 domains (Susceptibility, Seriousness, Benefits, Barriers, Knowledge, Health Motivation and Cue to Action). The confirmatory factor analysis (CFA) suggested that the Serbian HBMAI did not fit the original structure. The parallel analysis suggested that HBMAI in Serbian had 6 domains, instead of the original 7. The domain of "Knowledge" was removed. The domains of "Barriers", "Health Motivation" and "Cue to Action" preserved their original structure. The domains of "Susceptibility", "Seriousness" and "Benefits" were partially modified. The parameters on the CFA for the new modified HBMAI in Serbian were acceptable (goodness of fit index [GFI] = 0.946, comparative fit index [CFI] = 0.967, Tucker-Lewis index [TLI] = 0.963, root mean square error of approximation [RMSEA] = 0.044 and standardized root mean square residual [SRMR] = 0.078). This modified HBMAI version with 6 domains, not including the Knowledge domain, is recommended for use in research about influenza among people with chronic diseases in Serbian language.