慢性疼痛患者的症状通常持续几个月至几年。[73]Mäntyselkä P, Kumpusalo E, Ahonen R, et al. Pain as a reason to visit the doctor: a study in Finnish primary health care. Pain. 2001 Jan;89(2-3):175-80.http://www.ncbi.nlm.nih.gov/pubmed/11166473?tool=bestpractice.com 报告疼痛持续超过3个月的患者应积极接受治疗，而不建议等待自然改善。
背痛
大多数病例中，急性背痛发作在保守、对症治疗后消退。[74]Valat J, Goupille P, Rozenberg S, et al. Acute low back pain: predictive index of chronicity from a cohort of 2487 subjects. Joint Bone Spine. 2000;67(5):456-61.http://www.ncbi.nlm.nih.gov/pubmed/11143914?tool=bestpractice.com 但在过了急性期仍然持续的背痛常常长期持续。[75]Schiøttz-Christensen B, Nielsen GL, Hansen VK, et al. Long-term prognosis of acute low back pain in patients seen in general practice: a 1-year prospective follow-up study. Fam Pract. 1999 Jun;16(3):223-32.https://academic.oup.com/fampra/article/16/3/223/485577http://www.ncbi.nlm.nih.gov/pubmed/10439974?tool=bestpractice.com[76]Croft PR, Macfarlane GJ, Papageorgiou AC, et al. Outcome of low back pain in general practice: a prospective study. BMJ. 1998 May 2;316(7141):1356-9.https://www.bmj.com/content/316/7141/1356.fullhttp://www.ncbi.nlm.nih.gov/pubmed/9563990?tool=bestpractice.com[77]Thomas E, Silman AJ, Croft PR, et al. Predicting who develops chronic low back pain in primary care: a prospective study. BMJ. 1999 Jun 19;318(7199):1662-7.https://www.bmj.com/content/318/7199/1662.fullhttp://www.ncbi.nlm.nih.gov/pubmed/10373170?tool=bestpractice.com
肌筋膜性疼痛
症状特征性的长期持续，致残性疼痛通常存在，具有波动性。例如，在一个中心对慢性肌筋膜性疼痛患者进行的一项调查报告，在评估前，平均疼痛持续时间为63个月，范围为6 - 180个月。[78]Gerwin RD. Classification, epidemiology, and natural history of myofascial pain syndrome. Curr Pain Headache Rep. 2001 Oct;5(5):412-20.http://www.ncbi.nlm.nih.gov/pubmed/11560806?tool=bestpractice.com
纤维肌痛症
纤维肌痛很少完全缓解。[79]White KP, Harth M. Classification, epidemiology, and natural history of fibromyalgia. Curr Pain Headache Rep. 2001 Aug;5(4):320-9.http://www.ncbi.nlm.nih.gov/pubmed/11403735?tool=bestpractice.com 但在3年内进行随访时，大多数患者可出现症状明显改善，且药物依赖性降低。[80]Pöyhiä R, Da Costa D, Fitzcharles MA. Pain and pain relief in fibromyalgia patients followed for three years. Arthritis Rheum. 2001 Aug;45(4):355-61.https://onlinelibrary.wiley.com/doi/full/10.1002/1529-0131%28200108%2945%3A4%3C355%3A%3AAID-ART348%3E3.0.CO%3B2-Khttp://www.ncbi.nlm.nih.gov/pubmed/11501723?tool=bestpractice.com
