Prescription errors in older individuals with an intellectual disability: Prevalence and risk factors in the Healthy Ageing and Intellectual Disability Study

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Abstract

Prescribing pharmacotherapy for older individuals with an intellectual disability (ID) is a complex process, possibly leading to an increased risk of prescription errors. The objectives of this study were (1) to determine the prevalence of older individuals with an intellectual disability with at least one prescription error and (2) to identify potential risk factors for these prescription errors (age, gender, body mass index (BMI), frailty index, level of intellectual disability and living situation). The study population consisted of 600 older (≥50 years) individuals with an ID using one or more drugs who were randomly selected from the study cohort of the Healthy Ageing and Intellectual Disability (HA-ID) Study. The medication used at the time of measurement was screened for errors by a hospital pharmacist/clinical pharmacologist and a Master's student pharmacy using consensus methodology. Participants with one or more prescription errors were compared to participants without prescription errors by multivariate logistic regression to identify potential risk factors. The prevalence of individuals with one or more prescription errors was 47.5% (285 of 600 individuals; 95% confidence interval (CI) 43–52%). Relevant errors, defined as errors that actually do require a change of pharmacotherapy, were identified in 26.8% of the individuals (161 of 600 individuals; 95% CI 23–30%). Higher age (adjusted odds ratio (ORadj) 1.03; 95% CI 1.01–1.06), less severe intellectual disability (moderate: ORadj 0.48; 95% CI 0.31–0.74 and severe: ORadj 0.56; 95% CI 0.32–0.98), higher BMI (ORadj 1.04; 95% CI 1.01–1.08), higher frailty index (0.39–0.54: ORadj 2.4; 95% CI 1.21–4.77 and ≥0.55: ORadj 3.4; 95% CI 1.03–11.02), polypharmacy (ORadj 8.06; 95% CI 5.59–11.62) and use of medicines acting on the central nervous system (ORadj 3.34; 95% CI 2.35–4.73) were independently associated with the occurrence of prescription errors. Interventions targeted to high risk patients should be designed and implemented to improve pharmacotherapy in older individuals with an intellectual disability.

Highlights

► Drug prescribing to older individuals with an intellectual disability (ID) is complex. ► The prevalence of individuals with prescription errors in this population is 47.5%. ► Relevant errors were identified in 26.8% of the individuals. ► Age, level of ID, Body Mass Index and frailty index are potential risk factors for errors. ► Polypharmacy and drugs for the nervous system are also associated with errors.

Introduction

Inappropriate prescribing of pharmacotherapy occurs in about 20–40% of older individuals in the general population (Stafford et al., 2011, van der Hooft et al., 2005, Zaveri et al., 2010). Polypharmacy, i.e. concomitant use of five or more drugs, is also very common among these older people (Heuberger and Caudell, 2011, Stafford et al., 2011) and has been identified as a risk factor for the occurrence of prescription errors (Stafford et al., 2011).

The life expectancy of older individuals with an intellectual disability (ID) is increasing and age-related frailty seems to start at a younger age (Evenhuis, Hermans, Hilgenkamp, Bastiaanse, & Echteld, 2012). As a result, polypharmacy is very common among individuals with an intellectual disability aged 50 years and older. For example, antipsychotics, that have been associated with inappropriate prescriptions in older individuals in general (Stafford et al., 2011), are frequently used by individuals with an ID to treat psychiatric diseases and behavioural problems (de Kuijper et al., 2010). Additionally, chronic somatic diseases, such as epilepsy (Beavis, Kerr, & Marson, 2007) and gastro-esophageal reflux disease (Bohmer, Klinkenberg-Knol, Niezen-de Boer, & Meuwissen, 2000), frequently require pharmacotherapy. Other factors that may increase the complexity of prescribing drugs to older individuals with an ID are the often atypical symptoms of disease (Stolker, Koedoot, Heerdink, Leufkens, & Nolen, 2002); the impaired ability to communicate about disease and effectiveness of pharmacotherapy (Stolker et al., 2002); and the limited evidence for treatment of mental and behavioural problems with psychotropic drugs (Ulzen & Powers, 2008).

As a result, older individuals with an ID may be especially at risk of prescription errors. However, the prevalence of prescription errors and risk factors for such errors have not been established in this population. Therefore, the objectives of this study were (1) to determine the prevalence of older individuals with an intellectual disability with at least one prescription error and (2) to identify potential risk factors for these prescription errors.

Section snippets

Design

A cross-sectional study was performed to determine the prevalence of older individuals with an intellectual disability with at least one prescription error and to identify potential risk factors for these errors.

Setting and study population

The included research population in this study consisted of older individuals with an ID using one or more medicines who participated in the study titled “Healthy Ageing and Intellectual Disability” (HA-ID) (Hilgenkamp et al., 2011).

The cohort from the Erasmus MC HA-ID study (Hilgenkamp

Study population

Of the 1050 individuals with an ID included in the HA-ID study, 820 persons used one or more medicines at the time of inclusion of which 600 were randomly selected. In total 2773 prescriptions of these randomly selected individuals were screened for errors. Characteristics of the selected individuals and differences between this sample and the HA-ID cohort are presented in Table 2. Individuals in centralized settings were slightly overrepresented in our sample. Probably, individuals living in a

Discussion

This study, performed in a representative population, shows that prescription errors are frequently identified in older individuals with an intellectual disability. The prevalence of individuals with prescription errors in our population was 47.5% and relevant errors were identified in 26.8% of included individuals. Higher age, less severe intellectual disability, polypharmacy and use of drugs acting on the central nervous system showed a significant association with both all prescription

Conflict of interest

Authors declare that there are no conflicts of interest.

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