Factors associated with the use of gastrointestinal medicines amoung older people with intellectual disabilities in Ireland

Abstract

Background: People with intellectual disabilities (ID) experience multi-morbidity, multiple medication use and have complex health needs. Gastrointestinal (GI) disorders such as constipation and gastroesophageal reflux disorders (GORD) are commonly reported in this population and are among the comorbid conditions that can arise from childhood and have serious consequences. There are limited studies that investigate the use of GI medication comprehensively in people with ID. This includes medicines that manage constipation (e.g. laxatives) and acid-related disorders (e.g. Proton-Pump Inhibitors (PPIs)). Objectives: The thesis aimed to investigate use of the most prevalent GI medicines in older people with ID including two GI therapeutic classes; Laxatives and PPIs. This involved exploring their patterns of use, considering population demographic and clinical characteristics, examining the dosage regimen, the relevant reported indications, the length of use (particularly for PPIs), types of drug combinations (particularly for laxatives) and identifying factors that are significantly associated with their use. Methods: Data for this thesis is drawn from the Intellectual Disability Supplement to The Irish Longitudinal Study on Ageing (IDS-TILDA), a representative study of people with ID aged 40 years and over in Ireland. Data was taken from two waves; Wave 2 (n=677) (conducted in 2013/2014) and Wave 3 (n=549) (conducted in 2016/2017). Furthermore, data from the first wave of IDS-TILDA (conducted in 2009/2010) (n=736) was used to expand analysis of laxative use. Descriptive statistics, bivariate analyses and multiple logistic regression were carried out for this thesis. Furthermore, descriptive comparisons between different waves of the IDS-TILDA study was carried out for both laxatives and PPI use. Results: PPI use: About 28% of the population in Wave 2 reported use of PPIs. Almost 70% of PPIs were used at high doses. Over half reported using PPIs for more than a year and over 4 in 10 reported using PPIs without clear indications. Factors associated with PPI use, after adjusting for confounders, were older ages (≥50 years), severe/profound level of ID and reporting any PPI indications (GORD, peptic ulcers, use of Non-Steroidal Anti-inflammatory Drugs (NSAIDs) and use of antiplatelets). The use of PPIs increased to 35% in Wave 3 (a 7% increase since Wave 2). Over six in ten of participants who reported PPI use in Wave 2 continued to report PPI use in Wave 3. High doses of PPIs were used by a large proportion of participants in Wave 3 (69.9%). PPIs were more likely to be used by older ages (65+), those with severe/profound level of ID or by those who live in residential care at both waves of the IDS-TILDA. There were still some PPIs users who did not report clear indications for their use in Wave 3 IDS-TILDA (37.3%). Laxative use: Prevalence of laxative use in Wave 2 of IDS-TILDA was 41.5% (n=281). Of these, 74.3% (n=209) reported chronic constipation. About 4 in 10 (n=113) laxative users reported using two or more laxatives, within which, 60% (n=67) were using a combination from the same laxative class. Reporting laxative use increased from Wave 1 to Wave 3 from 37.5% to 44.4%. Although the use of laxatives was prevalent in this population, their use was not ubiquitous among those who had constipation or met Rome III criteria. In addition, some combinations of laxatives were identified and considered illogical (intraclass laxative combination). Further analysis indicated that the use of laxatives was also linked to substantial exposure to constipation risk factors in this population such as exposure to anticholinergics, medicines and conditions that contributed to constipation. The factors that significantly associated with laxative use in this population, after adjusting for confounders, were reporting chronic constipation, living in residential care, exposure to anticholinergics and receiving soft food or thickening fluids. Conclusion: This is the first study to assess the use of PPIs and laxatives comprehensively in an older population with ID. The study identified long-term PPI use with high doses and unclear indications suggesting an inappropriate PPI prescribing practice for this population. The use of laxatives was very prevalent especially among those in residential care or those exposed to constipation risk factors. The use of laxatives was not sufficient to manage constipation with use of some combinations that were considered inappropriate. Managing constipation in this population should not be restricted to giving laxatives but also to reduce and treat exposure to constipation risk factors.