Catquest questionnaire: re-validation in an Australian cataract population (original) (raw)
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Validity of a visual impairment questionnaire in measuring cataract surgery outcomes
Journal of Cataract & Refractive Surgery, 2008
Cataract patients, recruited from a hospital waiting list, completed the IVI questionnaire. The scale was assessed for fit to the Rasch model. Unidimensionality, item and person fit to the model, response category performance, differential item functioning (DIF, whether different subgroups respond differently) and targeting of item difficulty to patient ability were assessed.
Cat-PROM5: a brief psychometrically robust self-report questionnaire instrument for cataract surgery
Eye, 2018
Purpose To develop a short, psychometrically robust and responsive cataract patient reported outcome measure suitable for use in high-volume surgical environments. Methods A prospective study in which participants completed development versions of questionnaires exploring the quality of their eyesight using items harvested from two existing United Kingdom developed parent questionnaires. Participants were 822 patients awaiting cataract surgery recruited from 4 cataract surgical centres based in the UK. Exclusion criteria were other visually significant comorbidities and age o50 years. An iterative multi-stage process of evaluation using Rasch and factor analyses with sequential item reduction was undertaken. Results A definitive item set of just five items delivered performance in accordance with the requirements of the Rasch model: no threshold disordering, no misfitting items, Rasch-based reliability 0.90, person separation 2.98, Cronbach's α 0.89, good targeting of questions to patients with cataract with pre-operative item mean − 0.41 logits and absence of significant floor or ceiling effects, minor deviations of item invariance, and confirmed unidimensionality. The test-re-test repeatability intra-class correlation coefficient was 0.89 with excellent responsiveness to surgery, Cohen's d − 1.45 SD. Rasch calibration values are provided for Cat-PROM5 users. Conclusions A psychometrically robust and highly responsive five-item cataract surgery patient reported outcome measure has been developed, which is suitable for use in highvolume cataract surgical services.
Rasch Analysis of the Quality of Life and Vision Function Questionnaire
Optometry and Vision Science, 2009
Purpose. The Quality of life and Vision Function Questionnaire (QOL-VFQ) was developed using classical test theory to assess outcomes of cataract surgery. The aim of this study was to examine the psychometric properties of this questionnaire using Rasch analysis in a cataract population. Methods. The 17-item QOL-VFQ was self-administered to 389 patients waiting to undergo cataract surgery. The QOL-VFQ and its five subscales were assessed for fit to the Rasch model. Rasch analysis was used to estimate interval level measures of "visual ability" from ordinal scores for the QOL-VFQ and its five subscales. Unidimensionality, item fit, response category performance, and targeting of items to patients were assessed. Results. The QOL-VFQ and its five subscales showed ordered category thresholds. Despite removal of two misfitting items the person separation reliability was high and the QOL-VFQ could distinguish among three strata of patient ability. However, there was suboptimal targeting of patient ability to item difficulty as most of the patients had higher levels of visual functioning. None of the subscales demonstrated acceptable psychometric properties. Conclusions. These results support the good overall functioning of the QOL-VFQ in patients with cataract. However, adding more items, that suit the more able patients including those who are awaiting cataract surgery in the fellow eye, will help improve the targeting. (Optom Vis Sci 2009;86:E836-E844)
Investigative Ophthalmology & Visual Science, 2003
PURPOSE. The Activities of Daily Vision Scale (ADVS) has been extensively validated by traditional methodology. In the current study, Rasch analysis was used to explore further the validity of the ADVS and to determine whether improvements could be made. METHODS. Forty-three patients with cataract underwent visual acuity (VA) and contrast sensitivity (CS) testing and completed the ADVS. The data were Rasch analyzed and the value of response scale and item reduction explored. A shortened version and the original ADVS were tested for criterion validity by determining correlations with VA and CS. RESULTS. The ADVS data contained nonnormally distributed items and items with ceiling effects and empty response categories. Therefore, items benefited from shortening the response scale, the optimum length being three responses. There was poor targeting of item difficulty to patient ability, because many patients with cataract were sufficiently able that they had no difficulty with many activities. Items were eliminated if the task was too easy or did not fit with the overall concept of visual disability determined by the Rasch model. A reduced ADVS version was established that had adequate precision, equivalent criterion validity, and improved targeting of item difficulty to patient ability, but this version was still not ideal. CONCLUSIONS. Despite careful traditional validation, the ADVS data contained inadequacies exposed by Rasch analysis. Through Rasch scaling, particularly with response scale reduction, the ADVS can be improved, but additional questions seem to be needed to suit the more able, including patients undergoing second eye cataract surgery. There remains a need to develop Rasch-scaled measures of visual disability for use in ophthalmic outcomes research. (Invest Ophthalmol Vis Sci.
Eye, 2018
Background Cataract surgery is the most frequently undertaken NHS surgical procedure. Visual acuity (VA) provides a poor indication of visual difficulty in a complex visual world. In the absence of a suitable outcome metric, recent efforts have been directed towards the development of a cataract patient-reported outcome measure (PROM) of sufficient brevity, precision, and responsiveness to be implementable in routine high volume clinical services. Aim To compare and contrast the two most promising candidate PROMs for routine cataract surgery. Method The psychometric performance and patient acceptability of the recently UK developed five-item Cat-PROM5 questionnaire was compared with the English translation of the Swedish nine-item Catquest-9SF using Rasch-based performance metrics and qualitative semistructured interviews. Results Rasch-based performance was assessed in 822 typical NHS cataract surgery patients across four centres in England. Both questionnaires demonstrated good to excellent performance for all metrics assessed, including Person Reliability Indices of 0.90 (Cat-PROM5) and 0.88 (Catquest-9SF), responsiveness to surgery (Cohen's standardized effect size) of 1.45 SD (Cat-PROM5) and 1.47 SD (Catquest-9SF) and they were highly correlated with each other (R = 0.85). Qualitative assessments confirmed that both questionnaires were acceptable to patients, including in the presence of ocular comorbidities. Preferences were expressed for the shorter Cat-PROM5, which allowed patients to map their own issues to the questions as opposed to the more restrictive specific scenarios of Catquest-9SF. Conclusion The recently UK developed Cat-PROM5 cataract surgery questionnaire is shorter, with performance and patient acceptability at least as good or better than the previous 'best of class' Catquest-9SF instrument.
The New Zealand medical journal, 2019
AIMS The 'Impact on Life' (IoL) questionnaire is used to prioritise publicly funded cataract surgery in New Zealand, however, it has not been formally validated for ophthalmic use. The Catquest-9SF questionnaire is widely used to assess vision-related quality of life (VRQoL) but has not been validated in New Zealand. This study evaluates the validity of the IoL and Catquest-9SF questionnaires for measuring VRQoL in New Zealand. METHOD Formal ethics approval was obtained. Participants completed the IoL and Catquest-9SF questionnaires before and three months after routine cataract surgery. Rasch analysis was used to investigate all qualitative questionnaire responses. Results were correlated with the change in patient visual acuity. RESULTS There was a 100% response rate at follow-up (41 participants). Disordered probability thresholds were observed for all IoL questions but no Catquest-9SF questions. All IoL questions demonstrated unsatisfactory mean-square fit statistics. Di...