High-volume chiropractic practices have long been favored by doctors seeking to provide subluxation correction to as many people as possible. Militant chiropractic opponents have accused such practices of being "patient mills," implying they are not in the best interest of patients.

Yet, a review of medical research literature provides ample scientific evidence that quality of care is often closely linked to the provider's experience. This association between the volume of procedures performed by a provider, and the success of those procedures, has been demonstrated in numerous studies, including:

** A report in the July 2002 issue of Stroke: Journal of the American Heart Association. According to the Association, "patients are more likely to survive a stroke caused by a burst blood vessel if they are admitted to a hospital that treats these strokes more often ... The correlation between mortality and treatment volume persisted even when the researchers examined multiple variables that might contribute to it." The researchers noted that prior studies have shown better survival rates at higher volume facilities for patients with other complex medical needs, including coronary artery bypass surgery, carotid endarterectomy and HIV. – Citation: "Association Between Subarachnoid Hemorrhage Outcomes and Number of Cases Treated at California Hospitals," Naomi S. Bardach, et. al., Stroke, 2002;33:1851.

** A nationwide study sponsored by the Agency for Healthcare Research and Quality and published in the April 11, 2002 issue of The New England Journal of Medicine. Researchers examined the mortality rate associated with six different types of cardiovascular procedures and eight types of major cancer resections between 1994 and 1999 (total number of procedures, 2.5 million). They found that patients undergoing cardiovascular or cancer procedures for any of the conditions could significantly reduce their risk of operative death by selecting a high-volume hospital. – Citation: "Hospital Volume and Surgical Mortality in the United States," John D. Birkmeyer, M.D., et. al. The New England Journal of Medicine, 346:1128-1137.

** A retrospective analysis of 27,986 colon cancer patients aged 65 years and older undergoing surgery for colon cancer between 1991 and 1996, published in the Journal of the American Medical Association, Dec. 20, 2000. Researchers noted, "Survival following high-risk cancer surgery, such as pancreatectomy and esophagectomy, is superior at hospitals where high volumes of these procedures are performed." – Citation: "Influence of Hospital Procedure Volume on Outcomes Following Surgery for Colon Cancer, Deborah Schrag, M.D.; et. al., Journal of the American Medical Association, Vol. 284 No. 23.

** A study conducted by researchers from The Children's Hospital of Philadelphia, published in a November 2000 supplement of Circulation, a journal of the American Heart Association. "High-volume medical institutions such as The Children's Hospital of Philadelphia tend to have better survival rates for HLHS surgeries," the senior author of the paper noted. One reason given for the superior outcomes was "greater experience." – Citation: "Surgery for Congenital Heart Disease Survival After Reconstructive Surgery for Hypoplastic Left Heart Syndrome: A 15-Year Experience From a Single Institution," William T. Mahle, M.D., et. al., Circulation, 2000;102:III-136.

** A report by researchers from the University of Alabama at Birmingham, published May 25, 2000 in The New England Journal of Medicine. Results showed heart attack patients treated at hospitals experienced in performing large numbers of primary angioplasty procedures have higher survival rates. "There is an inverse relation between mortality from cardiovascular causes and the number of elective cardiac procedures (coronary angioplasty, stenting, or coronary bypass surgery) performed by individual practitioners or hospitals," the report concluded.  – Citation: "The Volume of Primary Angioplasty Procedures and Survival after Acute Myocardial Infarction," John G. Canto, M.D., et. al, The New England Journal of Medicine, 342:1573-1580.

Based on the clinical experience of numerous doctors of chiropractic, supported by these and other medical research studies, the World Chiropractic Alliance finds strong evidence that the adage "practice makes perfect" may apply – as it does to many other skills – to chiropractic adjusting as well. Criticism of, or opposition to high-volume chiropractic practices based solely on the number of patients who receive care, without regard to the outcomes of that care, is unfounded and unsupported by any valid research.