Abstract
Oral health literacy describes the capacity to obtain, process and understand oral health information, and is recognized as an important determinant of health. Numerous conceptual models of health literacy are presented in the literature, although very few have been empirically validated.
Aim: The aim of the study was to test Nutbeam’s Conceptual model of health literacy as a risk in a clinical dental setting. Based on the model, we hypothesized that patients addressed with communication sensitive to oral health literacy will improve their gingival status and oral hygiene compared to the patients addressed with communication not sensitive to oral health literacy.
Methods: A convenience sample was recruited from the waiting list for the University Dental Clinic, Tromsø, Norway. Participants had to be older than 20 years, have no severe visual impairment, and speak Norwegian. Individuals returning signed consent forms by mail, after receiving written information and invitation to participate in the study, were called to the dental clinic for study participation. In a randomised, examiner- and participant- blinded, controlled clinical trial. A sample of 133 adults were randomly allocated to experimental group (n=64, 54% women, mean age 50 years) and control group (n=69, 49% women, mean age 46 years). In order to detect medium-size effects (Cohen’s d = 0.5) with a power of 0.80 (ɑ = 0.05, two-tailed) a priori sample size power calculation was conducted. A stratified randomization was done to balance the control and experimental groups for age. In the experimental group, communication was tailored to patients’ oral health literacy levels using suitable communication techniques. Communication with the control group was not adapted to oral health literacy level. The Adult Health Literacy Instrument for Dentistry (AHLID) was used to assess oral health literacy level. Gingival status was the primary outcome variable, and oral hygiene status the secondary outcome variable. The clinical measurements were conducted pre- intervention and 6 months post-intervention. The study was registered in clinicaltrials.gov (ID: NCT 01118143). Ethical approval was granted by the Regional Ethical Committee. A Cohen’s d of 0.2 was considered a small effect, 0.5 a medium effect and 0.8 a large effect.
Results: Two participants were lost to follow-up due to drop- outs in both groups, while an additional three participants were lost in the control group due to other reasons. The ANCOVA showed a significant between-group effect finding that the experimental group reduced the post-intervention mean gingival (p<0.000) and plaque index (p<0.000) significantly more than the control group when controlled for baseline index scores. Adjusted Cohen’s d indicated large effect sizes between groups in both mean gingival index (- 0.98) and mean plaque index (-1.33).
Conclusions: Although the conceptual model of health literacy as a risk has some limitations, communication sensitive to oral health literacy seems to have a positive effect on clinical outcomes such as gingival status and oral hygiene.
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