1 3 Rheumatol Int (2015) 35:1005–1013 DOI 10.1007/s00296-014-3191-z Rheumatology INTERNATIONAL ORIGINAL ARTICLE - VALIDATION STUDIES Development of a bedside pain assessment kit for the classification of patients with osteoarthritis Eric Osgood · Jeremiah J. Trudeau · Thomas A. Eaton · Mark P. Jensen · Arnold Gammaitoni · Lee S. Simon · Nathaniel Katz Received: 22 July 2014 / Accepted: 9 December 2014 / Published online: 16 December 2014 © Springer-Verlag Berlin Heidelberg 2014 brass rod reliability was inconclusive. Patients were clas- sified empirically into four groups: “All abnormal find- ings” (primary and secondary hyperalgesia and dysfunc- tional DNIC); “all normal findings”; and two intermediate groups. The “all abnormal findings” group had more neu- ropathic pain symptoms, and lower WOMAC total, stiff- ness, and activity scores than the “all normal findings” group. Simple BSTK procedures, consolidated in a kit, reliably classified OA patients into subgroups based on sensory profile, suggesting that OA patients differ in underlying pain mechanisms. Further research is needed to confirm these subgroups and determine their validity in predicting response to treatment. Keywords Osteoarthritis · Pain · Sensory testing · Diffuse noxious inhibitory control · Hyperalgesia · Allodynia Abbreviations APAP Acetaminophen BSTK Bedside sensory testing kit DNIC Diffuse noxious inhibitory control HA Hyperalgesia/allodynia HNCS Heterotopic noxious conditioning stimulus ICC Intra-class correlation coefficient LTT Light touch threshold NRS Numerical Rating Scale NSAIDs Nonsteroidal anti-inflammatory drugs OA Osteoarthritis PPT Pressure pain threshold PQAS Pain Quality Assessment Scale QDS Questionnaire Development Systems QST Quantitative sensory testing WOMAC Western Ontario McMaster Osteoarthritis Questionnaire Abstract There are no standardized bedside assess- ments for subtyping patients with osteoarthritis (OA) based on pain mechanisms. Thus, we developed a bed- side sensory testing kit (BSTK) to classify OA patients based on sensory profiles potentially indicative of pain mechanism. After usability and informal reliability testing (n = 22), the kit was tested in a formal reliability study (n = 20). Patients completed questionnaires and sen- sory testing: pressure algometry to detect hyperalgesia; repeat algometry after heterotopic noxious conditioning stimulation to measure diffuse noxious inhibitory control (DNIC); light touch using Von Frey filaments; and cold allodynia using a brass rod. The procedure was brief and well tolerated. Algometry and filament testing were highly reliable [intra-class correlation coefficients (ICCs) 0.71– 0.91]; DNIC was acceptably reliable (ICCs 0.53–0.91); E.O., J.T., and T.E. are no longer working at Analgesic Solutions. E. Osgood · J. J. Trudeau · T. A. Eaton · N. Katz (*) Analgesic Solutions, 232 Pond Street, Natick, MA 01760, USA e-mail: nkatz@analgesicsolutions.com T. A. Eaton University of Connecticut, Storrs, CT, USA M. P. Jensen University of Washington, Seattle, WA, USA A. Gammaitoni Nuvo Research, West Chester, PA, USA L. S. Simon SDG LLC, West Newton, MA, USA N. Katz Tufts University School of Medicine, Boston, MA, USA