Validation of the Norwegian VISA-G Questionnaire

The Victorian Institute of Sport Assessment-Gluteal Questionnaire (VISA-G) questionnaire have already been developed and used as a measurement tool in research on English speaking GTPS populations.The VISA-G questionnaire is based on other Health-related patient-reported outcomes (HR-PROs) from Victorian Institute of Sports tendon study Group. The investigators will test the construct validity with two other HR-PROs (Harris Hip Score and Oswestry disability index). To investigate test-retest reliability, the patients will fill out a second VISA-N-G one week after baseline. To test responsiveness, the patients will fill out VISA-N-G 7 weeks after baseline together with the two other HR-PROs, and a Global Rating of Change scale.

Harris Hip Score (HHS) is an HR-PROs questionnaire used for assessing outcome after total hip replacement, femoral neck fractures and osteoarthritis. It is expected to take 5 minutes to complete and is based on 10 items. It is scored from 0 to 100, where 100 is the best outcome, <70 is considered a poor result. HHS has shown to be a responsive measure and shows a strong correlation in the physical domain of The short form Health survey (SF36) and high correlation to the Nottingham Health Profile.

Oswestry disability index (ODI) is a widely used HR-PROs used for spinal disorders. Its asking about the patients perceived disability and is scored from 0 to 100%, where 0% indicates no disability and 100% indicates most disability. ODI is cross-cultural adapted into Norwegian and psychometric properties was concluded acceptable for assessing self-reported functional status of Norwegian-speaking patients with low back pain.

In a Numeric rating scale (NRS) the patients rate their pain intensity between 0 and 10. Zero represents "no pain at all" and 10 represents "the worst pain ever possible". NRS correlates highly to other pain assessment tools. A change of two points is detected as being clinically significant. In this project the investigator will ask for the patient's current pain, average pain the last week, worst pain last week, and least pain last week.

A Global Rating of Change scale (GROC) scale is designed to quantify a patient's improvement or worsening over time, the scale ask about the current and previous health status and then calculates the difference. The scale is "global" and allows the patient themselves to subjectively decide their health status. Scales between 7 and 11 seems to be the compromise between patient preference, adequate discriminative ability and test-retest reliability. The investigator will use an 11-point scale from - 5 to 5 where - 5 = worsening, 0 = unchanged and 5 = completely recovered. An 11-point scale has shown test-retest reliability with ICC 0.90, minimum detectable change of 0.45 points and minimally clinically important change 2 points.