The study, led by Kristin Sofie Waldum-Grevbo and colleagues including Solveig Holen, Tore Wentzel-Larsen and Åse Sagatun, surveyed 1,425 thirteen-year-olds recruited from 48 lower secondary schools across 19 municipalities in Southeast and Central Norway. The sample deliberately spanned urban and rural communities ranging from villages of roughly 1,000 residents to cities of 700,000, and achieved a 71 percent response rate among invited students. Girls made up 50.3 percent of participants, and the vast majority reported Norwegian as their home language, lived with both parents, and perceived their family’s economic situation as ordinary. The data were drawn from the baseline of the GuideMe intervention study, collected in two waves during the 2022/23 and 2023/24 school years, making this one of the more robust population snapshots of early adolescence available in the Nordic region.

At the heart of the research is a concept known as health-related quality of life, or HRQoL — a measure that captures how health shapes physical, psychological and social functioning, and an explicit target of the United Nations’ Sustainable Development Goal 3. The researchers measured it using the Norwegian version of KIDSCREEN-27, a widely validated questionnaire covering five dimensions: physical well-being, psychological well-being, autonomy and parent relations, peer and social support, and school environment. Health literacy was assessed with the ten-item Health Literacy Among School-Aged Children instrument, which operationalizes the OECD-aligned definition — the knowledge, motivation and skills to access, understand, evaluate and apply health information — across five dimensions: theoretical knowledge, practical knowledge, critical thinking, self-awareness and citizenship. Self-efficacy was captured with the Norwegian five-item General Self-Efficacy Scale, rooted in Albert Bandura’s social-cognitive theory. All three instruments showed strong internal consistency, with Cronbach’s alpha values ranging from 0.81 to 0.90.

The descriptive results confirmed patterns that have haunted adolescent health research for years. Boys scored significantly higher than girls on health literacy, self-efficacy, and every single HRQoL subscale. Girls’ mean T-scores on KIDSCREEN ranged from 43.99 to 49.77, while boys’ ranged from 48.98 to 52.33, with the widest gaps in physical and psychological well-being. Compared with normative data spanning ages 8 to 18, the girls in this sample reported substantially lower physical and psychological well-being — a discrepancy the authors attribute in part to the narrow age range and in part to the timing of data collection shortly after the COVID-19 pandemic, whose documented toll on adolescent girls’ mental health may linger well beyond lockdowns.

But the study’s central question was not simply who scores higher. The researchers wanted to know whether self-efficacy mediates — statistically explains — the association between health literacy and quality of life. Using a causal mediation framework implemented in the R statistical environment, they modeled what would happen with a hypothetical 10 percentage-point increase in health literacy on a 0-to-100 scale, an increment grounded in reality: a recent European comparative study found health literacy levels vary by 13.5 percentage points across participating countries. The hypothetical bump produced significant increases across all five KIDSCREEN subscales for both sexes. The largest total effect appeared for school environment, with estimated T-score increases of 2.47 for girls and 1.86 for boys — roughly a quarter and a fifth of a standard deviation, respectively, which is notable for a modest, population-level shift in a single determinant.

The mediation results were striking. The proportion of the effect channeled through self-efficacy was significant for every subscale in both sexes, ranging from 30 percent for physical well-being among girls to 76 percent for peer and social support among boys — though the latter estimate came with a wide confidence interval and deserves caution. For psychological well-being, self-efficacy accounted for about 45 percent of the association in girls and 63 percent in boys. In other words, a substantial share of the benefit that comes with understanding health information appears to flow through the confidence to use it. The pattern fits neatly with Bandura’s theory: mastery experiences, social support and role models build self-efficacy, and self-efficacy determines whether knowledge and skills are actually translated into action and coping. An adolescent who believes she can successfully apply what she knows may be better equipped to engage in health-promoting behaviors and weather health-related challenges — and that, in turn, may be reflected in how well she feels and functions.

Why would the school environment subscale show the strongest total effect? The authors offer a plausible mechanism: health literacy overlaps conceptually with the competencies that drive learning. Students who can access, evaluate and apply information may engage more effectively with schoolwork and perceive their school environment more positively. Notably, the total effect estimates tended to be larger for girls than boys across all subscales, possibly because thirteen-year-old girls typically show higher emotional awareness and psychological distress and may be more receptive to health information. The confidence intervals for boys and girls overlapped, however, so the authors urge restraint in interpreting that pattern — it is a hypothesis generator, not a conclusion.

The team was careful about the limits of its design. Because the data are cross-sectional, the temporal assumptions underpinning causal mediation cannot be verified; the authors explicitly label the findings exploratory. Sensitivity analyses probed how much unmeasured confounding would be needed to overturn the results, and the direct effect estimates proved largely robust across subscales in both sexes, with one exception — peer and social support among boys — showing greater vulnerability. School-level clustering, measured by intra-class correlation coefficients between 0.003 and 0.03, was deemed negligible. All measures were self-reported, leaving room for social desirability bias, and item-level correlations between the health literacy and self-efficacy instruments (Spearman coefficients of 0.14 to 0.35) confirmed the two constructs, while related, are conceptually distinct.

The implications, if the associations hold causally, are considerable. Global health policy documents, European frameworks and Norway’s national strategy all emphasize strengthening population health literacy, and the education sector is the natural arena — it reaches nearly all children across socioeconomic backgrounds. Finland, whose children rank among Europe’s health literacy leaders, credits a standardized framework of health literacy learning objectives woven through the entire school program. Norway’s national guideline for school health services already mandates individual health-promoting consultations with all thirteen-year-olds, precisely to build health literacy, encourage positive behaviors and bolster self-efficacy, while identifying students who need follow-up. Evidence from German school nursing, where health literacy was measured before and after nurse-led health education, suggests schools and school health services jointly hold real potential to lift students’ literacy. Yet effectiveness studies of these strategies remain scarce.

What makes this study resonate beyond Norway is its population-level arithmetic. As Geoffrey Rose famously argued, even modest individual-level shifts in a health determinant can yield substantial benefits when applied across an entire population. If a ten-percentage-point improvement in adolescent health literacy is associated with measurable gains in physical, psychological and social well-being — with self-efficacy carrying a third to three-quarters of that association — then school-based literacy interventions become not just educational policy but mental and physical health infrastructure. The authors conclude that longitudinal studies are now needed to pin down the temporal ordering and causal nature of these relationships. Until then, the message for educators, school nurses and policymakers is tantalizingly concrete: teaching teenagers to understand health information may matter most when it also teaches them to believe they can act on it.

Subject of Research: The mediating role of self-efficacy in the association between adolescent health literacy and health-related quality of life.

Article Title: Adolescents’ health literacy and health-related quality of life: The mediating role of self-efficacy

Article References: Waldum-Grevbo, K. S., Holen, S., Wentzel-Larsen, T., & Sagatun, Å. (2026). Adolescents’ health literacy and health-related quality of life: The mediating role of self-efficacy. Public Health in Practice, 12, Article 100849. https://doi.org/10.1016/j.puhip.2026.100849

Image Credits: AI Generated

DOI: 10.1016/j.puhip.2026.100849

Keywords: adolescent health, health literacy, self-efficacy, health-related quality of life, KIDSCREEN, school health services, public health, Norway, mediation analysis, well-being, social-cognitive theory, health promotion