Intra-session absolute and relative reliability of pressure pain thresholds in the low back region of vine-workers: effect of the number of trials

Abstract

BackgroundPressure pain thresholds (PPT) are commonly used to quantify mechanical pain sensitivity of deep structures. Excellent PPT reliability has been previously reported among the low back of healthy subjects. However, there is a lack of studies assessing PPT over the low back of workers exposed to biomechanical risk factors of low back pain. Thus, the purpose of this study was threefold: (1) to evaluate the intra-session absolute and relative reliability as well as minimal detectable change (MDC) values of PPT within 14 locations covering the low back region of vine-workers and (2) to determine the number of trial required to ensure reliable PPT assessments and (3) to assess the effect of modifier factors such as gender, age, body mass index (BMI) and pain intensity on PPT reliability.MethodsTwenty-nine vine-workers voluntarily participated in this study. Twenty-two reported low intensity of low-back pain while seven were pain-free. PPTs were assessed among 14 anatomical locations in the lower back region. Three trials were performed on each location with an interval time of at least one minute. Reliability was assessed computing intraclass correlation coefficients (ICC), standard error of measurement (SEM) for all possible combinations between trials. Bland-Altman plots were also generated to assess potential bias in the dataset. Finally, a repeated measure analysis of variance (RM-ANOVA) with the number of trials used as within subject factor was performed on (1) PPT, (2) ICC and (3) SEM values.ResultsICC ranged from 0.86 to 0.99 for all anatomical locations and for all possible combinations between trials. SEM for comparison between trial 1–2, 2–3, 1–3 and, 1-2-3 ranged from respectively, 36.7–77.5, 27.8–77.7, 50–95.2 and, 39.3–80.8 kPa. ICC and SEM remained similar to the ones obtained for the entire population when taking modifier factors in consideration. The visual analysis of Bland-Altman plots suggested small measurement errors for all anatomical locations and for all possible combinations between trials.ConclusionsThe assessment of PPTs of the lower back among vine-workers was found to have excellent relative and absolute reliability. Moreover, reliable measurements can be equally achieved when using the mean of three PPT measurement or with the first one.

Reliability of morning, before‐dinner, and at‐bedtime home blood pressure measurements in patients with hypertension

“…The 95% confidence interval of the d was calculated as d ± t n−1 × √(SDd) 2 /n, where t n−1 corresponds to the value of t distribution with n−1 degrees of freedom, and n corresponds to the number of patients. 22 If the 95% confidence interval of the d did not include zero, the presence of fixed bias would be confirmed. We assessed the proportional bias by determining the linear regression between the averages and the differences of HBP values.…”

“…We assessed the fixed bias by calculating the 95% confidence interval of the . The 95% confidence interval of the was calculated as ± t n−1 × √(SDd) 2 /n, where t n−1 corresponds to the value of t distribution with n−1 degrees of freedom, and n corresponds to the number of patients . If the 95% confidence interval of the did not include zero, the presence of fixed bias would be confirmed.…”

Relative and absolute test-retest reliabilities of pressure pain threshold in patients with knee osteoarthritis

“…The reported SEM and MDC in the present study are similar to what has been reported in other studies. Balaguier et al [19] tested PPT's in the low back region of vine-workers and reported a SEM ranged from 53.5 to 77.5 kPa and MDC ranged from 148.4 to 214.7 kPa (mean PPT = 459.5-516.0 kPa in trial 1 and mean PPT = 468.7-540.8 kPa in trial 2) between the first and second trials. Walton and colleagues [38] tested at the trapezius muscle and at tibialis anterior and obtained SEM ranged from 18.2 to 73.8 kPa and MDC ranged from 42.7 to 171.3 kPa (mean PPT = 251.8 kPa and 334.1 kPa).…”

“…Continuous and intense nociceptive input from a damaged joint may contribute to sensitization by enhanced pain responses, the spread of pain to larger body areas, and outside the symptomatic joint [8,13,14]. Previous studies have demonstrated PPT to have a high relative reliability in various anatomical locations like knee [15,16], neck [17,18], and lower back [19,20] both in patients and in healthy humans. However, the reliability of PPT is influenced by factors such as gender, age, investigator and [19,21].…”

“…Previous studies have demonstrated PPT to have a high relative reliability in various anatomical locations like knee [15,16], neck [17,18], and lower back [19,20] both in patients and in healthy humans. However, the reliability of PPT is influenced by factors such as gender, age, investigator and [19,21]. Although, studies have concluded that PPT is a useful pain assessment tool in patients with KOA [22,23] the standard error of measurement (SEM), intra-and interclass correlation coefficients (ICCs), and minimum detectable change (MDC) have not been fully evaluated in KOA.…”