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Study Shows No Correlation Between Dosing Frequency and Medication Compliance

June 6th, 2007 at 5:12 am · · Enhancements · No Comments

Source:
New Study Suggests Number of Pills Not a Factor When it Comes to Daily Adherence to Medication





Regimen Simplification: Compliance Enhancement Or Not?

An ongoing controversy in patient compliance is whether or not frequency of dosing has an impact on adherence to a medication regimen. A study presented at the 19th Annual Meeting of the Academy of Managed Care Pharmacy1 in April 2007 suggests that “there is no correlation between the daily number of pills a patient is prescribed to take and how well a patient will adhere to a dosing regimen.”


The Study

The one-year, retrospective cohort study analyzed over 19,000 records of health service reimbursement from U.S. health plans within the Medstat MarketScan database, and looked at the prescription refill rates of different CCBs formulated for different daily dosing regimens (once daily, twice daily and three times daily dosing). All patients were 18 years of age and older and were patients with a physician-visit for high blood pressure. Several CCBs are available in different versions which have various defined dosing instructions (once daily to three times daily). CCBs with a co-pay > $20 were included in the analysis. The percentage of patients persisting on their prescriptions was measured at the end of one year. Persistence at 12 months was defined by looking 12 months, +/- 30 days from index date and seeing if the subject had a refill.
The study found that the range of persistence for the once daily drugs varied widely from 17% to 59%. There was no noticeable difference in drugs intended to be given once daily, twice daily, and three times daily. The twice daily/three times daily 1-year persistence rates ranged from 44% to 58%.


Commentary

First, I admit to discomfort in discussing a study that, as far as I can determine, has yet to be published in a peer-reviewed journal and is, in fact, presented in a press release that includes not only a blatant promotion for a specific medication (Asacol) but also a self-laudatory paragraph about Procter & Gamble, the manufacturer, that begins, “Three billion times a day, P&G brands touch the lives of people around the world. The company has one of the strongest portfolios of trusted, quality, leadership brands, including … .”

On the other hand, this approach, if charmless, does have the virtue of being obvious; any clinician or researcher reading this document would immediately be alert to possible built-in biases.

The write-up is, however, less straight-forward in presenting its case thusly,

“Despite the perception that dosing regimen is a primary factor influencing medication adherence, our study showed that this was not the case,” said co-author Simon Magowan, M.D., of Procter & Gamble Pharmaceuticals, the study’s sponsor. “This and other studies have suggested that reasons for non-adherence are often patient-specific and multifaceted.”

Designating the opposing view as a “perception” may be a tad misleading. In fact, the article/press release omits any reference to other studies which indicate a reduction in dosing frequency enhances compliance.

Finding such clinical trials requires no special research skills. Clicking on the search tag, regimen simplification at the end of this post, for example, pulls up a handful of studies of this sort that happen to have been covered here. A routine Google search for terms such as “medication compliance dosing frequency” finds many, many more. Heck, just Googling “Joyce Cramer” pulls up references to a bevy of convincing studies supporting the link between reduced dosing frequency and increased adherence.

Please note that I am not suggesting that the study reported in the press release is invalid or that the studies showing conflicting results are necessarily accurate; I am suggesting that the existence of those studies should have at least been acknowledged.

As for a conclusion on the issue, I quote [ahem] my own statement on this issue, originally written at least four years ago,

Decreasing the number of times per day a medication has to be taken is a frequently recommended compliance enhancement tactic and one supported by research. It is not, however, always the answer. Cheever assessed the level of adherence to once-a-day dosing by patients with Pneumocystis carinii pneumonia, whose treatment plan called for them to take one pill (with few side-effects) each day, any time during that day. Under these conditions, 29% of patients took more than 90% of the doses as prescribed, and a total of 54% were adherent at or above the 80% level (believed to be the lowest level at which clinical benefit could be expected). Moreover, a simple regimen is not always an option. While advances have been reported which could soon make single-pill, once-a-day AIDS treatment possible, for example, effective HIV treatment currently requires multiple combinations of medications taken several times a day. It is, in fact, the unusual case in which a physician would arbitrarily choose a more complex schedule when a simpler one is available.

None of this negates, for example, the potential utility of decreasing the number of doses in a given patient’s regimen or reducing side-effects when possible. It does mean that there are no simple answers to enhancing compliance.



Footnotes

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  1. The Academy of Managed Care Pharmacy has requested that their logo, which I had used in conjunction with this post, be removed. I am, of course, happy to do so↩

Tags: Enhancements