Algometry with a clothes peg compared to an electronic pressure algometer: a randomized cross-sectional study in pain patients

Abstract

BackgroundHypersensitivity of the central nervous system is widely present in pain patients and recognized as one of the determinants of chronic pain and disability. Electronic pressure algometry is often used to explore aspects of central hypersensitivity. We hypothesized that a simple pain provocation test with a clothes peg provides information on pain sensitivity that compares meaningfully to that obtained by a well-established electronic pressure algometer. "Clinically meaningful" was defined as a medium (r = 0.3-0.5) or high (r > 0.5) correlation coefficient according to Cohen's conventions.MethodsWe tested 157 in-patients with different pain types. A calibrated clothes peg was applied for 10 seconds and patients rated the pain intensity on a 0 to 10 numerical rating scale. Pressure pain detection threshold (PPdt) and pressure pain tolerance threshold (PPtt) were measured with a standard electronic algometer. Both methods were performed on both middle fingers and ear lobes. In a subgroup of 47 patients repeatability (test-retest reliability) was calculated.ResultsClothes peg values correlated with PPdt values for finger testing with r = -0.54 and for earlobe testing with r = -0.55 (all p-values < 0.001). Clothes peg values also correlated with PPtt values for finger testing with r = -0.55 (p < 0.001). Test-retest reliability (repeatability) showed equally stable results for clothes peg algometry and the electronic algometer (all r-values > 0.89, all p-values < 0.001).ConclusionsInformation on pain sensitivity provided by a calibrated clothes peg and an established algometer correlate at a clinically meaningful level.

Hypersensitivity and hyperalgesia in somatoform pain disorders

“…The pegs pressure exerted on an ear lobe is perceived as being consistently and clearly above the pain threshold [11]. The patient indicates the pain intensity on a numerical rating scale (NRS) on which 0 stands for "no pain" and 10 for "the most intense pain imaginable".…”

“…Both instruments have been validated and correlated in earlier studies [11]. Because absolute reference values do not exist for pain patients, hypersensitivity is defined relatively as a significantly lowered Production AB, Hörby, Sweden) by bilateral testing on the middle fingers.…”

“…For this type of algometry, we used a standardized peg with a clamping force of exactly 10 Newton at an extension of 5 mm (Type Algopeg, size 78x10 mm, polypropylene and nickel, spring reinforced in Switzerland, Annette Kocher, Inselspital Bern) [11]. The pressure is applied on the middle finger and the earlobes for 10 seconds each and is invariable.…”

Reliability and validity of a simple and clinically applicable pain stimulus: sustained mechanical pressure with a spring-clamp

“…During data collection of the present study, Egloff et al [21] published a similar study employing a clothes peg as the pain stimulus. The authors examined differences in pain response between two different clinical sub-groups (orthopaedic versus medical/psychosomatic pain), reported good correlation to pressure pain detection and tolerance thresholds and good test/re-test stability.…”

Test–retest reliability of a new technique with pressure algometry applied to teeth in healthy Chinese individuals

“…Furthermore, pressure algometry and PPTs have proven to be important psychophysical examination tools for obtaining measures of mechanical pain sensitivity in deep tissues (muscles, tendons, and joints), and they have been widely used in both experimental and clinical pain conditions (8,15,16). Pressure algometry and PPTs can be used in clinical research (17)(18)(19)(20)(21), for measuring the efficacy of therapeutic interventions for the treatment of pain (22)(23)(24), and in general psychophysiological research (25,26).…”