A Systematic Review and Meta-Analysis of Reading and Writing Interventions for Students with Disorders of Intellectual Development

Students with disorders of intellectual development (ID) experience challenges in reading and writing, indicating the need for research-based interventions. This systematic review and meta-analysis investigated the effects of reading and writing interventions for students aged 4-19 with disorders of ID using randomized controlled trials (RCTs) and quasi-experimental designs (QEDs). We conducted electronic searches of relevant databases, backward and forward searches, and contacted experts in the field. Based on predefined criteria, nine studies were included in the systematic review, and seven were included in the meta-analysis. The reading interventions included decoding strategies, often combined with sight-word and supplemental instructions appropriate to the participants' adaptive and cognitive skills. None of the studies aimed to increase writing skills. The overall mean effect size from the reading interventions for trained reading was large (g = 0.95, 95% CI = [0.51, 1.38]), for transfer reading small-to-moderate (g = 0.49, 95% CI = [0.20, 0.78]) and for transfer writing small (g = 0.04, 95% CI = [-0.36, 0.44]). Students with disorders of ID can benefit from reading interventions combining decoding strategies and sight word reading. There is a need for RCT and QED studies investigating writing interventions for students with disorders of ID only.