This study is the first to characterize and compare health literacy levels in a large group of pre-dialysis and in three groups of dialysis patients using two health literacy measures. The findings of the current study reveal differences in health literacy levels between patients in pre-dialysis, ICHD, PD and HHD. Findings on the two health literacy measures paralleled one another, with patients on home RRT (PD and HHD) scoring higher on the BHLS and generally achieving higher scores across several domains of the HLQ.
The lower prevalence of limited health literacy levels in home dialysis patients (PD 10.5% and HHD 0%) compared to patients in the pre-dialysis clinic (14.4%) and on ICHD (29.3%), confirms our initial hypothesis. Our results are also consistent with previous studies, which reported a prevalence of limited health literacy ranging from 16 to 32% for patients on ICHD [5–7, 12–14], and from 6 to 50% for patients on PD [6, 16, 17]. On the contrary, our predialysis population seems to have a better health literacy level compared to other cohort where a prevalence of 18 to 28% was reported [5, 6, 9–11]. To our knowledge, health literacy levels in patients on HHD has not been described before our study.
These results were expected since the nature of home dialysis requires that these patients rely more on their self-management and care skills, proactivity, and have a thorough understanding of the therapy. Even though the results were not statistically significant, patients on HHD tended to score higher on the BHLS than ICHD patients, however the small size of the group could explain why our results did not reach statistical significance. Moreover, the patients on home dialysis (PD and HHD), scoring higher on the BHLS, were younger, had a higher rate of education and of active employment status compared to the other groups. In previous studies, a lower educational attainment was associated with limited health literacy levels in ESRD and ICHD patients [5, 7, 10, 13, 19]. One may also argue that the higher health literacy scores observed in home dialysis patients might favour the choice of RRT towards home dialysis. This hypothesis would need further investigations to be confirmed.
Differences in the several domains of the HLQ have been found between the four groups. For example, patients on home RRT were more likely to feel understood and supported by their healthcare providers, which could be explained by a closer relationship between patients and the home dialysis healthcare professionals. Indeed, most patients on home RRT establish a trusting relationship with their healthcare providers, and have access to a 24 h/7days phone health care support. On the other hand, patients from the pre-dialysis clinic may see different nephrologists at each appointment and patients on ICHD may be followed by a different nephrologist each week.
Patients in the predialysis unit were more likely to report high abilities for health information appraisal. This could be explained by the fact that they have less to learn since explanations are provided on a regular basis and that they are provided with a book containing information on their CKD condition . There was no difference in the ability to find good health information among groups. Finally, patients in the predialysis clinic were less likely to feel confident in understanding health information well enough to know what to do compared to patients on ICHD. This could be explained by the smaller frequency of contact with healthcare professionals for patients in the predialysis clinic, compared to patients on ICHD who are followed up to three times a week by the medical team.
HHD is more complex than PD, which explains why this group scored higher on many domains of the HLQ. Peritoneal dialysis is a relatively easy procedure, which may explain why as many as 42% of PD patients have low education, 10.5% were identified as having low health literacy on the BHLS, and patients could be as old as 83 years old. Although health literacy levels in the ICHD group are lower, many patients do have a high literacy level, suggesting that patients may choose ICHD for reasons unrelated to the health literacy levels (lack of space for HHD, feeling of safety for ICHD, not wanting to bring CKD at home).
Recent literature supports that health literacy levels in CKD patients may be associated with clinical outcomes. It has been reported that participants with limited health literacy had lower estimated glomerular filtration rate  and higher self-reported cardiovascular diseases . In the ICHD population, limited health literacy was independently associated with an increased incidence of emergency department visits and dialysis related hospitalizations , increased risk of death , a lower risk of being referred for transplant evaluation , and worse blood pressure control than those with adequate health literacy . In PD patients, limited health literacy was not associated with an increased risk of infectious complications or hospitalization . The authors suggested that these results were related to the rigorous training that PD patients had to undergo, and that limited health literacy should not prevent patients from being considered eligible for PD [6, 17].
Younger age and being married were associated with a higher score in several health literacy domains of the HLQ. Similar findings have been described previously [7, 9, 15, 19].
Limitations of the present study include its descriptive, observational, monocentric nature, as well as the use of self-reported measures of health literacy. The high variability in refusal rates for participation may have underestimated the prevalence of low health literacy. This is especially true in the ICHD group where 25% of the patients refused to complete the HLQ. Finally, as the BSHL was only validated in English, it has been translated in French-Canadian by a bilingual Professor. However, this French version has not been validated.
Our study has several strengths. The high participation rate of patients on home dialysis (91%) enables us to provide a first reliable assessment of health literacy in this population, even though this estimation could be biased by the fact that HHD patients might be more educated and less reluctant to fill in questionnaires. We are therefore confident that our results will be useful for conducting future studies on health literacy in home dialysis patients. We used a validated health literacy tool (HLQ) with unique assessment of nine domains of health literacy. In contrast to older measures (REALM , TOFHLA ), its assessment goes beyond the domains of reading and writing ability, and matches more closely the definition of health literacy adopted by the WHO. Also, the French version of the HLQ was found to have very good internal consistency across the nine domains of health literacy .
In conclusion, there is a significant proportion of CKD patients, especially in predialysis clinic and in-centre hemodialysis, with limited health literacy. Development and update of education tools and methods in Nephrology will need to take into account the limited health literacy that is prevalent in our patients. A systematic health literacy level screening could be implemented in nephrology centres. As mentioned by the Assistant Secretary of Health, Howard Ko “The responsibility is ours as health professionals to communicate in plain language. Without clear communication, we cannot expect people to adopt the healthy behaviors and recommendations that we champion.” .