Readability of Commonly Used Quality of Life Outcome Measures for Youth Self-Report.

Self-report measures are central in capturing young people's perspectives on mental health concerns and treatment outcomes. For children and adolescents to complete such measures meaningfully and independently, the reading difficulty must match their reading ability. Prior research suggests a frequent mismatch for mental health symptom measures. Similar analyses are lacking for measures of Quality of Life (QoL). We analysed the readability of 13 commonly used QoL self-report measures for children and adolescents aged 6 to 18 years by computing five readability formulas and a mean reading age across formulas. Across measures, the mean reading age for item sets was 10.7 years (SD = 1.2). For almost two-thirds of the questionnaires, the required reading age exceeded the minimum age of the target group by at least one year, with an average discrepancy of 3.0 years (SD = 1.2). Questionnaires with matching reading ages primarily targeted adolescents. Our study suggests a frequent mismatch between the reading difficulty of QoL self-report measures for pre-adolescent children and this group's expected reading ability. Such discrepancies risk undermining the validity of measurement, especially where children also have learning or attention difficulties. Readability should be critically considered in measure development, as one aspect of the content validity of self-report measures for youth.