In our study we extended former results on the course of disease in patients receiving homeopathic treatment, now presenting data from an 8-year follow-up. These data consistently show substantial health improvements in patients under homeopathic treatment, which persisted through the whole observation period. Improvements were more pronounced in younger patients, females, and those with greater disease severity at baseline.
The methodological strengths of our study include consecutive enrolment of a large sample size, the participation of approximately 1% of all physicians certified to practice homeopathy in Germany and the use of standardised outcome instruments also used in studies on conventional therapy.
Moreover, our study provides a reasonably representative sample of all patients attending a doctor practicing classical homeopathy in Germany. The subset of patients responding to the 8-year follow up matched fairly well the data of the complete sample: although female adults were slightly overrepresented in this sample, data on age, complaint severity at baseline or duration of disease were nearly identical between those who responded after 8 years and those who did not. We therefore believe that selection bias is small and that our data are generalisable.
Our study was designed to evaluate homeopathic treatment in patients with various multiple diagnoses. This disallowed the use of disease-specific measurement instruments. Instead we used a numeric rating scale which is validated, often used [14
] and allowed for assessments of a specific complaint as well as for generalization and interpretation across various diagnoses. Using generic QoL questionnaires served the same purpose.
As patients were allowed to use conventional therapies and other complementary therapies during the study period, the observed improvements cannot be attributed to homeopathic treatment alone. The aim of this study, however, was not to test the effectiveness of homeopathic drug treatment, but rather provide an unbiased representation of contemporary homeopathic health care and its outcome in routine care.
The mean change of the severity ratings after 8 years was large. This may be partly explained by placebo and/or regression to the mean effects that our study was not designed to control. We thus cannot rule out overestimation of the treatment effect. The QoL improvements, on the other hand, may have been greater than recorded: The SF-36 is unlikely to overestimate changes, its mental scales have been found to be less sensitive than the mental und social scales of other instruments such as the Duke Health Profile [15
]. It is most unlikely that regression to the mean accounts for all QoL improvement that we have described: on the physical scale the adults scored even better than the average German population. Moreover, patients in this study suffered from long-term chronic diseases and nearly all of them were conventionally pretreated [10
]. This strengthens the likelihood that the improvement is not purely due to the natural history of the condition.
It is of note that the differences in the outcome between those patients who stopped treatment and those who still continued were small. Most patients reported improvements and only 5% of patients stopped treatment because of aggravations.
Moreover, only few diagnoses turned out as a predictive factor for treatment success. This might be taken as an indicator that the difference in outcome was similar for most diagnoses and that diagnosis was not a factor severely confounding our results.
Patients who used additional treatments had a worse outcome than those who did not. This presumably does not reflect the fact that these treatments were ineffective or even harmful, but is more likely a consequence from self-selection: patients who did not benefit from the homeopathic treatment are more likely to seek additional treatment.
To our knowledge, the present study is the first to evaluate systematically health effects under homeopathic treatment for such a long observation period and with a high follow-up rate. Güthlin et al., for example, investigated 933 chronically ill German homeopathy patients for a period of 30 months (only 129 providing data at that time point) and found comparable QoL effect sizes [16
]. In England, Spence et al. followed over 6.500 patients from a single homeopathic outpatient unit for an individual time period (maximum 6 years, average unknown) [17
]. Using a 7-point Likert scale of global clinical impression as an outcome measure they estimated that about 50% of all patients showed relevant improvements, a figure that matches our estimates. Several other investigations from different countries in Europe or America report similar health effects in various diseases within the first year after homeopathic treatment. Here the percentages of patients who experienced substantial improvements were consistently above 50%, [15
], although conventional medication was reduced [20