159 General discussion & future perspectives 8 responsiveness, supporting its psychometric quality. Furthermore, the extensive validation confirms the use of the OQUA as a domain specific PROM with an impact and a complaints’ part, to be used in the diverse types of otologic interventions and ENT patient groups. The OQUA was extensively field-tested with a sufficient number of patients. We aimed for a heterogeneous group of participants. Different patient characteristics were considered during the interviews, pilot testing and validating tests, including age, educational level and diagnosis for example. Although we aimed for a heterogenous group of participants, the Dutch culture is a diverse blend of cultures and religions, where the primary language spoken is not always the Dutch language.6 Next to the diverse range of cultures in the Netherlands, approximately 2 million people struggle with reading, writing, numeracy, and/or digital skills7. We excluded patients who were unable to read, speak and understand the Dutch language. All included participants for the validation study (chapter 4) and most patients of the patients in the implementation study (chapter 7) had already activated their online electronic health record (EHR) suggesting that the number of participants with low digital skills might be underrepresented in our research. The exclusion criteria might indicate that we have not completely mirrored the Dutch population with the sample of included respondents in our studies as we intended to do. Reflecting on the validation of other otologic PROMs, not all PROMs meet the necessary validity criteria. Each step of validation requires careful consideration. It is important to realise that there are three types of validity that can be distinguished: content-, criterion- and construct validity. What type of validity to measure and how is dependent of the situation and population8. We followed the COSMIN guideline and checklist.9 Unfortunately, there is no real consensus in the literature about the group size to evaluate validity. For factor analyses the rule of thumb is that the number of respondents needs to be according to a subject-to-variables ratio of 4:1 to 10:1 with a minimum of 100 subjects.10 With a 7-fold of the number of items (50) tested in the developmental phase of the OQUA (n=352) during the field testing, we believe to have sufficient numbers for proper content- and structural validity (part of the construct validity). According to the COSMIN checklist, for other measurement properties a smaller sample size with a minimum of 50 may be sufficient. Accordingly, 50 patients were included in the cohort for examining the OQUA’s responsiveness, but due to missing data, three patients had to be excluded. The remaining measurement properties to determine structural validity was thought to be a good representation of a general ENT practice and the number big enough to examine responsiveness with 124 patients included. Looking at other ear complaint PROMs, 121 patients were included in the overall validity analysis of the COMOT-1511, 91 in the CES4, 79 in the COQOL3, 52 in the SPOT-252 and 50 in the COMQ-12 1 respectively. As said these
RkJQdWJsaXNoZXIy MjY0ODMw