Christine H Meyer-Frießem1,2, Nadine Attal3,4, Ralf Baron5, Didier Bouhassira3,4, Nanna B Finnerup6,7, Rainer Freynhagen8,9, Janne Gierthmühlen5, Maija Haanpää10,11, Per Hansson12,13, Troels S Jensen6,7, Harriet Kemp14, Donna Kennedy14, Anne-Sofie Leffler13, Andrew S C Rice14, Märta Segerdahl15,16, Jordi Serra17, Soeren Sindrup18, Roma Solà17, Thomas Tölle19, Sigrid Schuh-Hofer20, Rolf-Detlef Treede20, Esther Pogatzki-Zahn21, Christoph Maier2, Jan Vollert14,20. 1. Department of Anesthesiology, Intensive Care, Palliative and Pain Medicine, University Hospital Bergmannsheil Bochum, Bochum, Germany. 2. Department of Pain Medicine, BG University Hospital Bergmannsheil GmbH, Ruhr-University Bochum, Bochum, Germany. 3. INSERM U-987, Centre d'Evaluation et de Traitement de la Douleur, CHU Ambroise Paré, Boulogne-Billancourt, France. 4. Université Versailles-Saint-Quentin, Versailles, France. 5. Division of Neurological Pain Research and Therapy, Department of Neurology, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany. 6. Department of Neurology, Aarhus University Hospital, Aarhus, Denmark. 7. Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark. 8. Department of Anaesthesiology, Critical Care Medicine, Pain Therapy & Palliative Care, Pain Center Lake Starnberg, Benedictus Hospital Tutzing, Tutzing, Germany. 9. Anaesthesiological Clinic, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany. 10. Department of Helsinki University Central Hospital, Helsinki, Finland. 11. Etera Mutual Pension Insurance Company Helsinki, Helsinki, Finland. 12. Division of Emergencies and Critical Care, Department of Pain Management and Research, Oslo University Hospital, Oslo, Norway. 13. Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden. 14. Pain Research, Department of Surgery and Cancer, Imperial College, London, UK. 15. H. Lundbeck A/S, Copenhagen, Denmark. 16. Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden. 17. Neuroscience Technologies, Ltd., Barcelona, Spain. 18. Department of Neurology, Odense University Hospital, Odense, Denmark. 19. Department of Neurology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany. 20. Center of Biomedicine and Medical Technology Mannheim CBTM, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany. 21. Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany.
Abstract
BACKGROUND AND AIMS: Healthy women have generally been found to have increased experimental pain perception and chronic pain has a higher prevalence in female as compared to male patients. However, no study has investigated whether pain intensity and pain perception thresholds are distinct or similar between sexes within various chronic pain entities. We investigated whether average pain intensities and pain thresholds assessed using quantitative sensory testing (QST) differed between women and men suffering from three distinct chronic pain conditions: Complex Regional Pain Syndrome (CRPS type I), peripheral nerve injury (PNI) or polyneuropathy (PNP), as compared to paired healthy volunteers. METHODS: QST data of 1,252 patients (669 female, 583 male) with PNI (n = 342), PNP (n = 571) or CRPS (n = 339), and average pain intensity reports from previously published studies were included. Absolute and z-values (adjusted for age and body region) of cold, heat, pressure (PPT) and pinprick pain thresholds were compared in generalized linear models with aetiology, duration of underlying pain disease and average pain intensity as fixed effects. RESULTS: Average pain intensity during the past four weeks did not differ between women and men, in both mean and range. In women absolute pain thresholds for cold, heat and pinprick were lower than in males across all diagnoses (p < .05). However, after z-transformation these differences disappeared except for PPT in CRPS (p = .001). DISCUSSION: Pain thresholds in patients show only minor sex differences. However, these differences mimic those observed in healthy subjects and do not seem to be linked to specific pathophysiological processes. SIGNIFICANCE: Female healthy participants and female patients with neuropathic pain conditions or CRPS I report lower pain thresholds compared to males, but pain intensity is similar and there is no sex difference in the extent to which the thresholds are altered in neuropathic pain or CRPS. Thus, the sex differences observed in various chronic pain conditions mimic those obtained in healthy participants, indicating that these differences are not linked to specific pathophysiological processes and are of minor clinical relevance.
BACKGROUND AND AIMS: Healthy women have generally been found to have increased experimental pain perception and chronic pain has a higher prevalence in female as compared to male patients. However, no study has investigated whether pain intensity and pain perception thresholds are distinct or similar between sexes within various chronic pain entities. We investigated whether average pain intensities and pain thresholds assessed using quantitative sensory testing (QST) differed between women and men suffering from three distinct chronic pain conditions: Complex Regional Pain Syndrome (CRPS type I), peripheral nerve injury (PNI) or polyneuropathy (PNP), as compared to paired healthy volunteers. METHODS: QST data of 1,252 patients (669 female, 583 male) with PNI (n = 342), PNP (n = 571) or CRPS (n = 339), and average pain intensity reports from previously published studies were included. Absolute and z-values (adjusted for age and body region) of cold, heat, pressure (PPT) and pinprick pain thresholds were compared in generalized linear models with aetiology, duration of underlying pain disease and average pain intensity as fixed effects. RESULTS: Average pain intensity during the past four weeks did not differ between women and men, in both mean and range. In women absolute pain thresholds for cold, heat and pinprick were lower than in males across all diagnoses (p < .05). However, after z-transformation these differences disappeared except for PPT in CRPS (p = .001). DISCUSSION: Pain thresholds in patients show only minor sex differences. However, these differences mimic those observed in healthy subjects and do not seem to be linked to specific pathophysiological processes. SIGNIFICANCE: Female healthy participants and female patients with neuropathic pain conditions or CRPS I report lower pain thresholds compared to males, but pain intensity is similar and there is no sex difference in the extent to which the thresholds are altered in neuropathic pain or CRPS. Thus, the sex differences observed in various chronic pain conditions mimic those obtained in healthy participants, indicating that these differences are not linked to specific pathophysiological processes and are of minor clinical relevance.