Objective: To investigate the frequency and types of improved nonmusculoskeletal symptoms reported after chiropractic spinal manipulative therapy.
Design: Retrospective information obtained by chiropractors through standardized interview of patients on return visit within 2 weeks of previous treatment.
Setting: The private practice of 87 Swedish chiropractors (response rate 81%).
Subjects: Twenty consecutive (presumably naive) patients per chiropractor (1504 valid questionnaires returned, 86% of optimal number of replies).
Intervention: Spinal manipulation with or without additional therapy provided by chiropractors.
Main outcome measures: Self-reported improved nonmusculoskeletal symptoms (reactions).
Results: At least I reaction was reported after the previous treatment in 21% to 25% of cases. Of these responses, 26% were related to the airway passages (usually reported as "easier to breathe"), 25% were related to the digestive system (mostly reported as "improved function"), 14% were classified under eyes/vision (usually reported as "improved vision"), and 14% under heart/ circulation (about half of these reported as "improved circulation"). The number of spinal areas treated was positively associated with the number of reactions.
Conclusion: A minority of chiropractic patients report having positive nonmusculoskeletal reactions after spinal manipulative therapy but such reports cluster predominantly around specific symptoms. It would be interesting to find out if these can be verified objectively and, if so, to investigate if they are caused by the treatment or if they are signs of natural variations in human physiology.