An estimated 50% of patients do not take their medicines as prescribed, which is decision intentional for an estimated 30% of these patients(1). Reasons for this intentional non-adherence are numerous and include a desire to reduce inconvenient effects, to avoid adverse effects, or a fear of medication dependence. For the remaining 70% of non-adherent patients, their behaviour is dominated by unintentional factors such as confusion and memory failure.(1)
Medication Organisation Devices (MODs) are an integral part of standard care to support patients suspected of being unintentionally non-adherent. Accurate data for the prevalence of their use are unavailable, however, conservative estimates indicate that in 2001 at least 100,000 people were using MODs in the UK; with an aging population, this number will have substantially increased over the past 13 years.(2)
MODs are usually a box or blister pack divided into days of the week with several compartments per day to allow for different dose timings. However, there is no definitive evidence for the effect(s) of MODs on adherence. The UK National Institute for Health Research Health Technology Assessment programme therefore funded a pilot randomised controlled study.
Provide an indication of the effect(s) of MODs and generate data to inform a full trial of their effectiveness and cost effectiveness.
Patients were randomised to receive their usual prescribed medication either in standard packaging or a MOD. Patients were eligible if community dwelling, aged 75 years or more, self-medicating at least three different solid orally administered medicines and identified as non-adherent through a pill count three weeks after provision of a new medication supply. This was likely unintentional non-adherence based on self-report questionnaire data. Post-randomisation, adherence for two months was measured by pill count.
Post ethical approval from NHS East of England, 29 community dwelling patients were recruited. Three participants subsequently withdrew and one was excluded due to level of visual impairment being unsafe for standard care medication packaging. Of the remaining 25 participants, 12 received standard medication packaging and 13 received their medication in a MOD.
Five (38%) participants receiving a MOD experienced an adverse event (AE) or serious adverse event (SAE). No AEs or SAEs were reported for the control group. The table below summarises the (S)AEs recorded. The median (IQR) increase in adherence was 11% (0, 45) for MOD participants experiencing an (S)AE compared with 5% (0, 17) for standard packaging participants. An adherence increase exceeding 40% was measured for 35% (95% CI 21%) of the medicines prescribed for participants experiencing an AE compared with 13% (95% CI 10%) for those with no reported AE.
The small sample size precludes determination of any definitive causal link between MODs and AEs. The relationship is, however, plausible; all of the participants described in the table were prescribed at least one medicine which may contribute to a fall and the increase in adherence for MOD participants was greater than for the control. The use of MODs appears to have resulted in a greater proportion of the prescribed medicine being administered and thereby increasing risk of iatrogenic events.(5)
The findings of this study are in agreement with previous studies designed to promote adherence which have reported increased mortality and healthcare costs for participants receiving the intervention.(6, 7) It is intuitive that increasing adherence to a medication may result in a dose related AE. It may therefore be prudent to review the prescribed dose of any medication with a high risk of dose related AEs (e.g. antihypertensives, hypoglycaemics, anticoagulants, and anticonvulsants) before introduction of an adherence intervention, and to monitor after its introduction to ensure treatment is optimised.
1. Gadkari AS, McHorney CA. Unintentional non-adherence to chronic prescription medications: how unintentional is it really? BMC Health Serv Res. 2012;12:98.
2. Nunney JM, Raynor DKT. How are multi-compartment compliance aids used in primary care? : Pharmaceutical Journal. 267 (7176) (pp 784-789), 2001. Date of Publication: 01 Dec 2001.; 2001.
3. Butt DA, Mamdani M, Austin PC, Tu K, Gomes T, Glazier RH. The risk of falls on initiation of antihypertensive drugs in the elderly. Osteoporos Int. 2013;24(10):2649-57.
4. British Medical Association and the Royal Pharmaceutical Society of Great Britain. British national formulary (version 67). London: BMJ Group and Pharmaceutical Press; 2014.
5. Routledge PA, O'Mahony MS, Woodhouse KW. Adverse drug reactions in elderly patients. Br J Clin Pharmacol. 2004;57(2):121-6.
6. Lenaghan E, Holland R, Brooks A. Home-based medication review in a high risk elderly population in primary care -- the POLYMED randomised controlled trial. Age & Ageing. 2007;36(3):292-7.
7. Pacini M, Smith RD, Wilson EC, Holland R. Home-based medication review in older people: Is it cost effective? PharmacoEconomics. 2007;25(2):171-80.
Competing interests: No competing interests