gms | German Medical Science

Background: Pain is a complex phenomenon with a sensory and emotional component influenced by physiological, psychological and social factors. Sex and gender are multidimensional constructs entangled closely with the biopsychosocial phenomenon of pain as an individual life experience. Although the literature suggests that sex and gender have a relevant impact on pain and pain (medication) therapy, the existing knowledge is transferred very less in practice and projects. The GESCO study aims to develop and pilot-test a practical, sex- and gender-sensitive intervention for CNCP receiving LTOT in primary care combining the current evidence.

Materials and methods: To extract and summarize the increasing body of research in this area and to tailor a pharmacological intervention for the study a literatureliterate search was conducted in PubMed. This literature search focused initially on systematic reviews (SR) and meta-analyses (MA) including sex differences in pharmacokinetics, pharmacodynamics of opioids and gender differences in pain perception and chronic pain. This first research was followed by a second, extended research beyond systematic reviews and meta-analyses inc. Two authors performed study selection and data extraction independently.

Results: Of 299 identified SRs and MAs, 35 met the inclusion criteria and were included in the analysis. Although sex-and-gender-specific-medicine (SGSM) is receiving more and more implementation in research, the terms sex and gender are often used interchangeable. The misuse of the terms lead to ambiguities regarding informative value of studies. This explains, among other things, the number of studies that meet our criteria. The selected literature showed how sex and gender interact to produce the differences in chronic pain. The analyses showed different types of sex and gender differences in pain. Such types may be quantitative such as the prevalence of chronic pain or qualitive differences. Qualitative sex influences in the nervous, hormonal, and immune systems show physiological differences in nociception and pain chronification. In human and animal studies a modulating role of sex hormones on the opioid receptors has been observed. Furthermore, clinical data showed sex-specific differences in dosage, side effects and addiction patterns of opioids. Women tend to need a lower dose with certain opioid and have more side effects of the opioid therapy. Not only sex influences pain, but gender also may influence the perception of pain and the effect of the pain therapy. Studies suggested that women show greater clinical pain, lower pain threshold and tolerance this could be due social norms and behaviors, but also due biological factors such as the menstrual cycle.

No research results are available on trans and non-binary individuals.

Conclusion: This analysis shows a substantial body of evidence about sex and gender influence on chronic pain and its therapy. At the same time, there should be better competency for sex and gender related factor and their influence without limitation on the level of research and clinical practice. These findings will be implemented in the GESCO Study with a focus on sensitizing and improving clinical skills in the assessment and treatment of chronic pain.