Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study).

BACKGROUND: Multiple questionnaires to screen for psoriatic arthritis (PsA) have been developed but the optimal screening questionnaire is unknown. OBJECTIVES: To compare three PsA screening questionnaires in a head-to-head study using CASPAR (the Classification Criteria for Psoriatic Arthritis) as the gold standard. METHODS: This study recruited from 10 U.K. secondary care dermatology clinics. Patients with a diagnosis of psoriasis, not previously diagnosed with PsA, were given all three questionnaires. All patients who were positive on any questionnaire were invited for a rheumatological assessment. Receiver operating characteristic (ROC) curves were used to compare the sensitivity, specificity and area under the curve of the three questionnaires according to CASPAR criteria. RESULTS: In total, 938 patients with psoriasis were invited to participate and 657 (70%) patients returned the questionnaires. One or more questionnaires were positive in 314 patients (48%) and 195 (62%) of these patients attended for assessment. Of these, 47 patients (24%) were diagnosed with PsA according to the CASPAR criteria. The proportion of patients with PsA increased with the number of positive questionnaires (one questionnaire, 19·1%; two, 34·0%; three, 46·8%). Sensitivities and specificities for the three questionnaires, and areas under the ROC curve were, respectively: Psoriatic Arthritis Screening Evaluation (PASE), 74·5%, 38·5%, 0·594; Psoriasis Epidemiology Screening Tool (PEST), 76·6%, 37·2%, 0·610; Toronto Psoriatic Arthritis Screen (ToPAS), 76·6%, 29·7%, 0·554. The majority of patients with a false positive response had degenerative or osteoarthritis. CONCLUSION: Although the PEST and ToPAS questionnaires performed slightly better than the PASE questionnaire at identifying PsA, there is little difference between these instruments. These screening tools identify many cases of musculoskeletal disease other than PsA.

Statistical strategies to assess reliability in ophthalmology.

Reliability of measurements and measurers is important so that we can trust the measurements we record. However, the statistical techniques used to assess reliability of measurements or measurers in the ophthalmic literature are often inappropriate, and not able to evaluate reliability between measurements/measurers. We review the techniques used in reliability studies for both continuous and categorical data, and describe appropriate statistical methods for particular study designs. We also highlight current techniques that are not appropriate in the analysis of reliability, but that are still commonly used in the ophthalmic literature. We hope that by highlighting these, we shall discourage their future use.

The development and assessment of a self-perceived quality of vision questionnaire to test pseudophakic patients.

PURPOSE: To develop and test a questionnaire to assess quality of vision in pseudophakic patients. METHODS: The problems with existing health measurement scales and the need for a new questionnaire are first discussed. Development of the new questionnaire from concept to completion is presented and all stages discussed. The questionnaire is then tested for internal consistency, reliability and validity. RESULTS: The Cronbach Alpha for internal consistency was 0.92. British Standards Institution repeatability coefficient was satisfactory at 6.6. Discriminant construct validity testing by extreme groups demonstrated excellent discrimination between patients with functionally significant posterior capsule opacification (PCO) and no significant PCO (Mann-Whitney U test, p = 0.001). CONCLUSION: The questionnaire is validated as a robust, stable measure of pseudophakic visual symptoms with a high degree of clinical utility. It should be invaluable for the many studies that compare outcomes from different forms of modern cataract surgery with implantation of different intraocular lenses.

Systems of analysis of posterior capsule opacification.

This paper demonstrates the wide variety of systems for the analysis of posterior capsular opacification (PCO). No single system has been proved to be a gold standard and it is difficult to comment on the advantages of one system over another with the limited current knowledge on the effects of PCO on vision. There are few studies that actually compare the different systems of analysis. Researchers must ensure that the systems they use for PCO analysis are objective and must give maximum consideration to ensuring potential systematic errors are reduced to a minimum. Further research is required into how the various types and locations of PCO affect vision and how well different systems of analysis perform.