Patient choice promotes adherence in preventive treatment for latent tuberculosis
T. W. Rennie, G. H. Bothamley, D. Engova, and I. P. Bates. Eur Respir J 2007; 30:728-735
The Study
This study’s abstract follows:
Data for all patients treated using 3RH or 6H for LTBI between 1998 and 2004 were analysed. In total, 675 patients attended for chemoprophylaxis. Of these, 314 received 3RH and 277 received 6H. From April 1, 2000, patients were offered a choice of regimen; 53.5% completed the regimen successfully, a further 10.3% potentially completed it successfully and 36.2% failed to complete treatment.
Logistic regression analysis suggested that successful completion was more likely in patients who were younger (an association that was lost after removing all patients aged <16 yrs), were offered a choice of regimen and attended all clinic visits before commencing treatment. Treatment was discontinued due to adverse reactions in 16 (5.1%) patients who were prescribed 3RH and 16 (5.8%) who were prescribed 6H. Treatment failure was most likely during the first 4 weeks of treatment for both regimens. At 13 weeks of treatment, more patients taking 6H had stopped compared with those completing the 3RH regimen. Drug costs were greater using 6H compared with 3RH.
In conclusion, offering a choice of regimen improves completion. Most patients chose the 3-month rifampicin and isoniazid treatment over the 6-month isoniazid treatment. Adverse drug reaction rates between the two regimens were similar.
Commentary
Offering patients treatment choices may indeed promote adherence, but I’m not convinced the results of this study are evidence of this hypothesis.
First, the study is complex. The population included patients treated by one of two methods, 3 months of rifampicin and isoniazid or 6 months of isoniazid, over a six year period. During the first two years, the treatment for a given patient was chosen by the doctor (the reasons one method or the other was chosen were not provided) while the patients were offered their choice of treatments over the last four years of the study.
That the majority of patients (78%) chose the shorter treatment is hardly surprising. (Nor is it surprising that more patients completed a three month course of treatment than a six month course of treatment.) Since the split between 3 month treatments and 6 month treatments among all patients was almost equal (3 month treatment: 53% of patients; 6 month treatment: 47% if all patients) the majority of the physician-assigned patients must have received the longer treatment.
I suggest that conclusions based on comparisons between these inherently dissimilar groups are, at best, tenuous.
Further, as is often the case in compliance studies, the definitions of successful completion, potentially successful completion, and failure to complete are rational but somewhat arbitrary:
appointment or a single negative urine test fully explained by the patient, and sufficient medication supplied to ensure that
there were no gaps in treatment. Failure to complete included the remainder, i.e. those who defaulted from clinic visits
without sufficient medication to ensure treatment completion.
And, for the purposes of this study’s statistics,
While these decisions can be justified and, indeed, may be necessary, it is unlikely that the definitions of adherence and nonadherence used in this research are a perfect match for the notions of adherence and nonadherence used in everyday clinical practice.
There are other, less overt, problems with this study enroute to the conclusion that patient choice enhances compliance but these should be sufficient to cast doubt on the unequivocal declaration of the title. A shame, that.