Wiekens, Nils (2025) Op de grens van diagnose: de effecten van diagnoseprotocolwijzigingen voor dyslexieprevalentie. Bachelor thesis, Academische Opleiding Leraar Basisonderwijs (AOLB).
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Abstract
The criteria for the formal diagnosis of the neurologically based learning disability dyslexia in the Netherlands have changed over the past 20 years. Over that same timespan the reported prevalence increased, this raises the question as to what extent this may be due to the changes in diagnostic protocols. Therefore, the goal of present study was to investigate possible differences, in terms of prevalence and cognitive profiles of dyslexia, resulting from the application of two different sets of diagnostic criteria, cf. PDDB 1.0 (2006) and PDDB 3.0 (2021), to one and the same group of Dutch primary school children. It was hypothesised that prevalence would be lower in PDDB 3.0 and that phonemic awareness would better predict reading ability in PDDB 3.0, whereas rapid automised naming would better predict reading ability in PDDB 1.0. A dual cross-sectional quantitative comparative design was applied to test our hypotheses for a study sample (n = 235) of primary school children, that was composed of an existing dataset from 2007, which was extended with current collected data. Included participants completed standardized Dutch reading(-related) tests, i.e., EMT, de Klepel-R, CB&WL, and FAT-R, in order to (1) gain insight in their word and pseudoword reading abilities, rapid automatised naming, and phonemic awareness, respectively, and (2) classify them into PDDB version-based subgroups. As to the latter, and based on the resulting test scores, 12 (46.2% of diagnosed) participants met the criteria of both protocols, 9 (34.6% of diagnosed) participants only fulfilled the criteria of PDDB 1.0, and 5 (19.2% of diagnosed) children only met those for the (current) PDDB 3.0 protocol. A McNemar test showed that the apparent difference in group size was not significant, however. Furthermore, it was found that the actual PDDB 3.0 protocol results in diagnoses where reading of existing words is better predicted by rapid automised naming and reading of pseudowords is better predicted by phonemic awareness. Due to methodological limitations, the resulting small numbers of children meeting the PDDB criteria in particular, interpretations of the results necessarily must remain tentative. However, the present study did show a possible effect of diagnostic criteria with regard to the prevalence rates, and the derived reading-related cognitive profiles of diagnosed students. Follow-up research, with a larger sample, is needed to further examine these effects.
| Item Type: | Thesis (Bachelor) |
|---|---|
| Supervisor name: | Groot, B.J.A. de |
| Degree programme: | Academische Opleiding Leraar Basisonderwijs (AOLB) |
| Differentiation route: | None [Bachelor AOLB] |
| Date Deposited: | 23 Jul 2025 09:55 |
| Last Modified: | 23 Jul 2025 09:55 |
| URI: | http://gmwpublic.studenttheses.ub.rug.nl/id/eprint/5689 |
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