An example on the value of non-randomisation in clinical trials in complementary medicine

Comparing Propensity Score Methods for Creating Comparable Cohorts of Chiropractic Users and Nonusers in Older, Multiply Comorbid Medicare Patients With Chronic Low Back Pain

OBJECTIVE

Patients who use complementary and integrative health services like chiropractic manipulative treatment (CMT) often have different characteristics than do patients who do not, and these differences can confound attempts to compare outcomes across treatment groups, particularly in observational studies when selection bias may occur. The purposes of this study were to provide an overview on how propensity scoring methods can be used to address selection bias by balancing treatment groups on key variables and to use Medicare data to compare different methods for doing so.

METHODS

We described 2 propensity score methods (matching and weighting). Then we used Medicare data from 2006 to 2012 on older, multiply comorbid patients who had a chronic low back pain episode to demonstrate the impact of applying methods on the balance of demographics of patients between 2 treatment groups (those who received only CMT and those who received no CMT during their episodes).

RESULTS

Before application of propensity score methods, patients who used only CMT had different characteristics from those who did not. Propensity score matching diminished observed differences across the treatment groups at the expense of reduced sample size. However, propensity score weighting achieved balance in patient characteristics between the groups and allowed us to keep the entire sample.

CONCLUSIONS

Although propensity score matching and weighting have similar effects in terms of balancing covariates, weighting has the advantage of maintaining sample size, preserving external validity, and generalizing more naturally to comparisons of 3 or more treatment groups. Researchers should carefully consider which propensity score method to use, as using different methods can generate different results.

Profiling quality of care for patients with chronic headache in three different German hospitals - a case study

BACKGROUND

Legal requirements for quality assurance in German rehabilitation hospitals include comparisons of providers. Objective is to describe and to compare outcome quality of care offered by three hospitals providing in-patient rehabilitative treatment exemplified for patients with chronic headache.

METHODS

We performed a prospective three center observational study on patients suffering from chronic headache. Patients underwent interventions commonly used according to internal guidelines of the hospitals. Measurements were taken at three points in time (at admission, at discharge and 6 months after discharge). Indicators of outcome quality included pain intensity and frequency of pain, functional ability, depression, quality of life and health related behavior. Analyses of differences amongst the hospitals were adjusted by covariates due to case-mix situation.

RESULTS

306 patients from 3 hospitals were included in statistical analysis. Amongst the hospitals, patients differed significantly in age, education, diagnostic subgroups, beliefs, and with respect to some pain-related baseline values (covariates). Patients in all three hospitals benefited from intervention to a clinically relevant degree. At discharge from hospital, outcome quality differed significantly after adjustment according to case-mix only in terms of patients' global assessment of treatment results. Six months after discharge, the only detectable significant differences were for secondary outcomes like improved coping with stress or increased use of self-help. The profiles for satisfaction with the hospital stay showed clear differences amongst patients.

CONCLUSION

The results of this case study do not suggest a definite overall ranking of the three hospitals that were compared, but outcome profiles offer a multilayer platform of reliable information which might facilitate decision making.

A review of the application of propensity score methods yielded increasing use, advantages in specific settings, but not substantially different estimates compared with conventional multivariable methods

OBJECTIVE

Propensity score (PS) analyses attempt to control for confounding in nonexperimental studies by adjusting for the likelihood that a given patient is exposed. Such analyses have been proposed to address confounding by indication, but there is little empirical evidence that they achieve better control than conventional multivariate outcome modeling.

STUDY DESIGN AND METHODS

Using PubMed and Science Citation Index, we assessed the use of propensity scores over time and critically evaluated studies published through 2003.

RESULTS

Use of propensity scores increased from a total of 8 reports before 1998 to 71 in 2003. Most of the 177 published studies abstracted assessed medications (N=60) or surgical interventions (N=51), mainly in cardiology and cardiac surgery (N=90). Whether PS methods or conventional outcome models were used to control for confounding had little effect on results in those studies in which such comparison was possible. Only 9 of 69 studies (13%) had an effect estimate that differed by more than 20% from that obtained with a conventional outcome model in all PS analyses presented.

CONCLUSIONS

Publication of results based on propensity score methods has increased dramatically, but there is little evidence that these methods yield substantially different estimates compared with conventional multivariable methods.

An analysis of sickness absence in chronically ill patients receiving complementary and alternative medicine: a longterm prospective intermittent study

Background

The popularity of complementary and alternative medicine (CAM) has led to a growing amount of research in this area. All the same little is known about the effects of these special treatments in every-day practice of primary care, delivered by general practitioners within the health insurance system. From 1994 to 2000 more than 20 German Company health insurances initiated the first model project on CAM according to the German social law. Aim of this contribution is to investigate the effectiveness of multi-modal CAM on chronic diseases within primary health care.

Methods

A long-term prospective intermittent study was conducted including 44 CAM practitioners and 1221 self-selected chronically ill patients (64% women) of whom 441 were employed. Main outcome measure is sick-leave, controlled for secular trends and regression-to-the mean and self-perceived health status.

Results

Sick-leave per year of 441 patients at work increased from 22 (SD ± 45.2) to 31 (± 61.0) days within three years prior to intervention, and decreased to 24 (± 55.6) in the second year of treatment, sustaining at this level in the following two years. Detailed statistical analysis show that this development exceeds secular trends and the regression-toward-the-mean effect. Sick-leave reduction was corroborated by data on self-reported improvement of patients' health status.

Conclusion

Results of this longterm observational study show a reduction of sick leave in chronically ill patients after a complex multimodal CAM intervention. However, as this is an uncontrolled observational study efficacy of any specific CAM treatment can not be proven. The results might indicate an general effectiveness of CAM in primary care, worthwhile further investigations. Future studies should identify the most suitable patients for CAM practices, the most appropriate and safe treatments, provide information on the magnitude of the effects to facilitate subsequent definitive randomised controlled studies that will help to position complementary and alternative medicine in health care.

[Treatment of inflammatory diseases of the upper respiratory tract -- comparison of a homeopathic complex remedy with xylometazoline]

INTRODUCTION

The primary objective of treatment of inflammatory diseases of the upper respiratory tract (rhinitis, uncomplicated sinusitis) with local decongestants is to relieve obstruction and to improve associated symptoms. Restoration of unrestricted respiration and drainage of the nasal sinuses reduce the risk of further complications (i.e. chronicity).

OBJECTIVE

To determine whether the therapeutic effects of the homeopathic complex remedy Euphorbium compositum nasal drops SN are comparable to those of xylometazoline with respect to efficacy and tolerability.

METHODS

Open, multicenter, prospective, active-controlled cohort study in patients with inflammatory processes and diseases of the upper respiratory tract. The primary outcome was to demonstrate non-inferiority of the homeopathic complex remedy to xylometazoline.

RESULTS

Clinically relevant reductions in the intensities of disease-specific symptoms were observed with both therapies. Non-inferiority of the homeopathic complex remedy to xylometazoline could be shown for all studied variables and in no case did the lower boundary of the 95% confidence interval cross the threshold of 0.5 score points. Tolerability was good with for both therapies.

CONCLUSIONS

This cohort study indicates a comparable efficacy and tolerability profile of the homeopathic complex remedy Euphorbium compositum nasal drops SN and the reference substance xylometazoline in patients with inflammatory processes and diseases of the upper respiratory tract.