Persistent upper gastrointestinal symptoms despite proton pump inhibitor therapy: Construct validity
For PASS inter-item analysis, individual phi correlation coefficients were calculated. Correlations were considered low-to-moderate if the coefficients fell between 0.4 and 0.6; moderate-to-high if greater than 0.6; and excellent if greater than 0.8.
Construct validity refers to how well the patient’s status is reflected by the PASS test compared with other standard questionnaires. It is determined by the degree of correlation (Spearman’s rank correlation p) between scores on the PASS scale and those on three other validated scales: GSRS, QoLRAD and RDQ.
Responsiveness to changes in patients’ symptoms due to treatment was evaluated by the use of ‘effect size’ and symptom improvement. The effect size reflects changes in symptoms standardized by the variability of the change. It is calculated using the change in score from pretreatment (visit 2) to four weeks of treatment (visit 3), divided by the baseline SD. Effect sizes between 0.4 and 0.8 were considered moderate-to-good; those greater than 0.8 were considered excellent. For comparison purposes, effect size also was calculated with data grouped by means of GSRS, RDQ and QoLRAD. Online shopping will cost you less – find nolvadex price here and enjoy the experience.