Article type
Year
Abstract
Introduction/Objective: To review the quality of clinical trial research in homeopathy and identify the extent of threats to validity of causal interpretations in these trials. In addition, we compared the type and extent of these threats to validity to research on conventional therapies.
Methods: A comprehensive, multiple-strategy search for all clinical trials published on homeopathic treatments was done. Inclusion criteria for studies: 1) published in English between 1945-1995; 2) examining an intervention for a clinical condition in a comparative trial, 3) be prospective and involve a parallel control group; 4) assess the outcome of the intervention using an empirical measure of some type. All trials were evaluated using an established method of quality assessment involving 33 validity criteria covering statistical conclusion, internal, construct and external validity. Reliability of criteria application is greater than 0.95.
Results: A total of 59 studies met the inclusion criteria and of these 79% were from peer-reviewed journals. In research design 29% used a placebo control, 51% used random assignment, and 86% failed to consider potentially confounding variables. In measurement 96% did not report the proportion of subjects screened, and 64% did not report attrition rate. An average of 17% of subjects dropped out in studies where this was reported. Of 229 outcome variables, 32% were significantly improved from homeopathic treatment, 39% were unaffected and 2% were made worse by the treatment. The probability of a positive outcome was significantly lower when randomization and placebo were used than when another method of group assignment or comparison to conventional therapy was used. There was practically no replication of or overlap in the conditions studied and most studies were relatively small and done at a single-site. Compared to research on conventional therapies the overall quality of studies was similar except that homeopathic studies were more prone to sampling biases and the use of multiple outcome measures than conventional therapy. Both conventional and homeopathic studies consistently fail to report on the reliability of outcome measures used to control for heterogeneity among groups. There is a higher proportion of placebo-controlled studies in homeopathic compared to conventional medicine research.
Discussion: Clinical homeopathic research is clearly in its infancy with most studies using poor sampling and measurement techniques, few subjects, single sites and no replication. While some of these methodological flaws may arise out of an attempt to identify specific effects of a "holistic" treatment approach, many of these problems are correctable even within such a paradigm given sufficient research expertise and support.
Methods: A comprehensive, multiple-strategy search for all clinical trials published on homeopathic treatments was done. Inclusion criteria for studies: 1) published in English between 1945-1995; 2) examining an intervention for a clinical condition in a comparative trial, 3) be prospective and involve a parallel control group; 4) assess the outcome of the intervention using an empirical measure of some type. All trials were evaluated using an established method of quality assessment involving 33 validity criteria covering statistical conclusion, internal, construct and external validity. Reliability of criteria application is greater than 0.95.
Results: A total of 59 studies met the inclusion criteria and of these 79% were from peer-reviewed journals. In research design 29% used a placebo control, 51% used random assignment, and 86% failed to consider potentially confounding variables. In measurement 96% did not report the proportion of subjects screened, and 64% did not report attrition rate. An average of 17% of subjects dropped out in studies where this was reported. Of 229 outcome variables, 32% were significantly improved from homeopathic treatment, 39% were unaffected and 2% were made worse by the treatment. The probability of a positive outcome was significantly lower when randomization and placebo were used than when another method of group assignment or comparison to conventional therapy was used. There was practically no replication of or overlap in the conditions studied and most studies were relatively small and done at a single-site. Compared to research on conventional therapies the overall quality of studies was similar except that homeopathic studies were more prone to sampling biases and the use of multiple outcome measures than conventional therapy. Both conventional and homeopathic studies consistently fail to report on the reliability of outcome measures used to control for heterogeneity among groups. There is a higher proportion of placebo-controlled studies in homeopathic compared to conventional medicine research.
Discussion: Clinical homeopathic research is clearly in its infancy with most studies using poor sampling and measurement techniques, few subjects, single sites and no replication. While some of these methodological flaws may arise out of an attempt to identify specific effects of a "holistic" treatment approach, many of these problems are correctable even within such a paradigm given sufficient research expertise and support.