The first comprehensive multicenter study of non-musculoskeletal benefits following chiropractic care was from Sweden.  Published in 1999, and with data from 1504 patients and 87 members of the Swedish Chiropractors’ Association, it reported that: 

 • About 1 in 4 (23%) of adult patients consulting chiropractors for musculoskeletal conditions experienced positive non-musculoskeletal benefits after chiropractic adjustment/manipulation.

• Positive benefits reported were most commonly respiratory disorders (26%), digestive disorders (25%), cardiac/circulatory problems (14%) and visual disturbances (14%).

• There was a positive dose-response gradient. Patients treated in more than one spinal region reported more nonmusculoskeletal benefits - of those patients treated in one spinal area 15% had a non-musculoskeletal benefit, in two spinal areas 22%, in three spinal areas 32% and in four spinal areas 35%.

This well-designed study, led by the prominent Danish researcher Charlotte Leboeuf-Yde, DC MPH PhD, provided better documentation of the type of anecdotal results reported daily by chiropractors and their patients. Because of the positive dose-response relationship it suggested that the more frequent nonmusculoskeletal improvements were in fact related to the chiropractic care given, rather than chance fluctuations, and through physiological as well as psychological mechanisms. However it did not prove that. Leboeuf-Yde, Axen et al. called for further studies to challenge or confirm their results, to be followed by controlled trials in areas of most promise.

The full article can be found at https://www.chiropracticreport.com/index.php/past-issues/view_category/4-2005, and it is Issue #5.