Association between non-adequate health literacy and cancer screening adherence. A meta-analysis

Objective: Individuals with non-adequate health literacy (NAHL) are more likely to have poor health outcomes and behaviors,including a limited use of preventive services. This study aimed at summarizing the evidence on the association between NAHL and adherence to cancer screening programs. Methods: PubMed, Scopus, and Web of Science were searched. Crosssectional studies conducted in any country, published through January 2020 and quantifying the association between NAHL and cancer screening adherence, were included. An adapted Newcastle-Ottawa Scale was used to assess quality. Inversevariance random-effects methods were used to produce pooled estimates: overall, by cancer and by HL tool. Results: Seventeen articles of heterogeneous quality were included in the systematic review and 45 analyses were combined. NAHL was found to negatively influence screening adherence in both the crude (n = 26) and adjusted (n = 19) pooled analyses, and the association was slightly stronger in the latter (OR = 0.70, 95%CI: 0.62-0.79 and aOR=0.66, 95%CI: 0.57-0.76, respectively). Moreover, NAHL was significantly associated with lower adherence in all the types of cancer screening investigated: breast cancer (n = 7), aOR=0.55, 95%CI: 0.38-0.78; cervical cancer (n = 4), aOR=0.63, 95%CI: 0.53-0.75; prostate cancer (n = 1), aOR=0.60, 95%CI: 0.36-0.99, and colorectal cancer (n = 7), aOR=0.85, 95%CI: 0.74-0.97. Lastly, tools measuring NAHL with reading comprehension/numeracy items yielded the strongest association with the outcome (n = 5, aOR= 0.53, 95%CI: 0.35-0.80), that was attenuated in tools with either self-reported comprehension items (n = 7, aOR=0.72, 95%CI: 0.65-0.80) or medical term recognition items (n = 7, aOR=0.74, 95%CI: 0.57-0.95). Conclusions: This study shows that NAHL may have a significant impact on adherence in all types of screening programs analysed, independently of the tools applied to measure it. Hence, it should be a useful focus for interventions to improve screening participation rates. Key messages: Non-adequate health literacy negatively influences cancer screening adherence. Efforts to promote the uptake of cancer screening programs should consider and address NAHL.