Illness perceptions and perceived functional health literacy in inflammatory bowel disease: a multicentre longitudinal study

Perceived Functional Health Literacy (HL) and Illness Perceptions (IPs) are key yet understudied determinants of self-care in Inflammatory Bowel Disease (IBD). Although cross-sectional studies suggest a relationship between these constructs, their temporal directionality and within-person dynamics remain unclear, as previous research has failed to distinguish stable between-person differences from true intra-individual change processes. To examine the longitudinal and reciprocal relationship between perceived functional HL and IPs in people living with IBD, separating within-person dynamics from stable between-person differences.

A multicenter prospective longitudinal study included 455 people living with IBD from nine Italian specialized centers, with data collected at baseline, 6, and 12 months. Perceived functional HL (self-reported difficulty in understanding written health information) was assessed using the Single Item Literacy Screener (SILS) and IPs via the Brief Illness Perception Questionnaire (BIPQ). Temporal associations were analyzed using a Bayesian Random-Intercept Cross-Lagged Panel Model (RI-CLPM).

Worsening IPs were temporally associated withsubsequent increases in perceived HL difficulties (posterior M = 0.18, 95% Credible Interval (CrI) [0.07, 0.28]); the reverse effect was not credible (posterior M = 0.25, 95% CrI [− 0.04, 0.53]). Older age, male gender, and Crohn’s disease were stable predictors of both constructs. SILS showed strong persistence (β = 0.63); BIPQ showed greater variability with mean reversion (β = −0.27).

The relationship between functional HL and IPs is asymmetric and within-person driven: deteriorating illness perceptions were temporally associated with subsequent increases in perceived HL difficulties, but not vice versa, highlighting the need for integrated psychological support in IBD care. Random-intercept cross-lagged panel model The authors wish to thank all patients who took part in this study for their time and valuable contribution. Open access funding provided by Università degli Studi Magna Graecia di Catanzaro within the CRUI-CARE Agreement.

Department of Clinical and Experimental Medicine, Magna Graecia University of Catanzaro, Catanzaro, 88100, Italy Caterina Mercuri, Silvio Simeone & Patrizia Doldo Department of Biomedicine and Prevention, University of Rome Tor Vergata, Via Montpellier 1, Rome, 00133, Italy Department of Nursing and Obstetrics, Wroclaw Medical University, ul. Bartla 5, Wrocław, 51-618, Poland Direction of Health Professions, ASST Cremona, Viale Concordia 1, Cremona, 26100, Italy SITRA-Scientific Direction, Fondazione Policlinico Gemelli IRCCS, Rome, 00168, Italy The authors declare no competing interests. The study was conducted in accordance with the Declaration of Helsinki and approved by Ethics Committee (approval number: 0023486/23).

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