Chiropractic care and risk for acute lumbar disc herniation: a population-based self-controlled case series study

Chiropractic care is popular for low back pain, but may increase the risk for acute lumbar disc herniation (LDH). Low back pain is a common early (prodromal) symptom of LDH and commonly precedes LDH diagnosis. Our objective was to investigate the association between chiropractic care and acute LDH with early surgical intervention, and contrast this with the association between primary care physician (PCP) care and acute LDH with early surgery. Using a self-controlled case series design and population-based healthcare databases in Ontario, Canada, we investigated all adults with acute LDH requiring emergency department (ED) visit and early surgical intervention from April 1994 to December 2004. The relative incidence of acute LDH with early surgery in exposed periods after chiropractic visits relative to unexposed periods was estimated within individuals, and compared with the relative incidence of acute LDH with early surgery following PCP visits. 195 cases of acute LDH with early surgery (within 8 weeks) were identified in a population of more than 100 million person-years. Strong positive associations were found between acute LDH and both chiropractic and PCP visits. The risk for acute LDH with early surgery associated with chiropractic visits was no higher than the risk associated with PCP visits. Both chiropractic and primary medical care were associated with an increased risk for acute LDH requiring ED visit and early surgery. Our analysis suggests that patients with prodromal back pain from a developing disc herniation likely seek healthcare from both chiropractors and PCPs before full clinical expression of acute LDH. We found no evidence of excess risk for acute LDH with early surgery associated with chiropractic compared with primary medical care.