A Study on the Psychometric Properties of Revised-nonverbal Pain Scale and Original-nonverbal Pain Scale in Iranian Nonverbal-ventilated Patients

BACKGROUND AND AIMS The nonverbal pain scale is one of the instruments which study pain in nonverbal-ventilated patients with regard to the changes of behavioral and physiological indices. The purpose of the study is to survey the psychometric properties of revised-nonverbal pain scale (R-NVPS) and original-nonverbal pain scale (O-NVPS) in ventilated patients hospitalized in critical care units. MATERIALS AND METHODS Four nurses studied pain in sixty patients hospitalized in trauma, medical, neurology, and surgical critical care units using R-NVPS and O-NVPS at six times (before, during, and after nociceptive and nonnociceptive procedures). The test was repeated in 37 patients after 8-12 h. RESULTS Cronbach's alpha coefficient for R-NVPS and O-NVPS was 0.8 and 0.76, respectively. The inter-rater correlation coefficient during different times was r = 0.89-0.96 for R-NVPS and r = 0.80-0.87 for O-NVPS. Test-retest correlation coefficient for R-NVPS and O-NVPS was r = 0.55-0.86 and r = 0.51-0.75, respectively. The meaningful difference in pain score between nociceptive and nonnociceptive procedures (P < 0.001) and a higher pain score in patients who confirmed pain (P < 0.001) showed a discriminant and criterion validity for both scales of NVPS, respectively. CONCLUSIONS R-NVPS and O-NVPS can both be used as valid and reliable scales in studying pain in ventilated patient. However, in comparing the items, "respiration" (R-NVPS) had a higher sensitivity than "physiology II" (O-NVPS) in assessing pain.