The Western Ontario Shoulder Instability (WOSI) questionnaire is a 21-item questionnaire to evaluate quality of life in patients with shoulder instability. Completing the questionnaire is time-consuming because each item is evaluated on a visual analog scale. Telephone or email versions of the score are appealing alternatives to administering it during the standard in-person patient visit; however, their validity and reliability remain unknown.
(1) Does the numerical scale (NS) version of the WOSI correlate with the original WOSI and Quick-DASH? (2) Do telephone and email administration of the NS-WOSI have good reliability and consistency? (3) Compared with the original WOSI form, does the NS form lead to faster completion for patients and quicker data extraction for researchers?
Between 2014 and 2019, 50 patients with a documented history of shoulder dislocation with persistent symptomatic shoulder instability, whether anterior, posterior, or multidirectional; patients scheduled for surgery; and patients with traumatic or nontraumatic injuries were prospectively recruited from the outpatient clinic of two university hospitals acting as Level 1 trauma centers and sports traumatology tertiary referral centers. The median (IQR) age was 28 years (24 to 36), and 80% (40 of 50) were men. Most (52% [26 of 50]) patients had two to five lifetime shoulder dislocations. Validity of the NS-WOSI was assessed using the Pearson correlation coefficient during an in-person visit; the original WOSI questionnaire (or its previously validated French-language version), NS-WOSI, and Quick-DASH questionnaires were administered in a random order. After a minimum 7-day interval, 78% (39 of 50) of patients completed the phone interview, and 74% (37 of 50) of patients completed the email version of the NS-WOSI score to evaluate NS-WOSI’s reliability using the intraclass correlation coefficient (ICC), which was interpreted as poor (< 0.5), moderate (0.50-0.75), strong (0.75-0.90), and very strong (> 0.90). The standard error of measurement (SEM) was used to evaluate variability around the true score, with a low value indicating a high reliability. The 95% minimal detectable change (MDC95%) was calculated to evaluate the minimal change in score that was not related to measurement errors. Lastly, the Cronbach alpha was used to assess internal consistency (intercorrelation strength), where a value > 0.70 was considered good. The time needed for the patient to complete the various versions and for researchers to extract data was recorded.
The NS-WOSI score was very strongly correlated with the original WOSI score (r = 0.96 [95% confidence interval (CI) 0.93 to 0.98]; p < 0.001). Although telephone-acquired and email-acquired data for the NS-WOSI questionnaires were correlated with the NS-WOSI (telephone r = 0.91 [95% CI 0.83 to 0.95]; p < 0.001; email r = 0.84 [95% CI 0.71 to 0.91]; p < 0.001), the ICC was higher for telephone interviews (0.92 [95% CI 0.86 to 0.96] versus email 0.80 [95% CI 0.64 to 0.89]), indicating that although both had good reliability, the phone interview was more suitable. The phone interview was also preferable to email regarding SEM (3% [52 of 2100 points] versus 6% [132 of 2100 points]) and the MDC95% (7% [144 of 2100 points] versus 17% [366 of 2100 points]). The 95% CI of the MDC acquired by email was superior to the reported minimum clinically important difference for the original WOSI (7% [152 of 2100 points]), meaning that an error of measurement could wrongly be interpreted as a clinically significant change in score. Internal consistency was deemed good, with a Cronbach alpha of 0.96 (95% CI 0.92 to 98) and 0.89 (95% CI 0.79 to 0.94) for NS-WOSI telephone and email, respectively. The time to complete the NS-WOSI was reduced compared with the original WOSI (221 ± 153 seconds versus 266 ± 146 seconds, mean difference -45 seconds [95% CI -72 to -12]; p = 0.009). Lastly, data extraction was faster (62 ± 15 seconds versus 209 ± 52 seconds, mean difference -147 seconds [95% CI -164 to -130]; p < 0.001) with the NS-WOSI than with the original WOSI.
The NS-WOSI in person, by telephone, or by email is a valid, reliable, and timesaving alternative to the original WOSI questionnaire. However, the reliability of data acquisition by telephone interviews was superior to that of email.
Given that there were no important differences in performance for the NS-WOSI, regardless of whether it was administered in person or by phone, we suggest that physicians use both interchangeably based on patient convenience. However, we do not recommend using the email version, especially for research purposes, since it was not as reliable when compared with in-person administration. The responsiveness of the modified NS-WOSI, as well as factors influencing response rates to phone interview, are questions that remain to be explored.