The effect of chronic Benzodiazepine use on consumer safety : accidents, injuries, and cognitive failures

Benzodiazepines are a class of medications with a broad range of pharmacological actions including anti-anxiety, muscle-relaxant, antiepileptic, hypnotic, and memory impairing effects. Benzodiazepines became a popular medication due to their relative safety of use and their fast-acting effects. However, increasingly research has established a range of detrimental effects, including reduced efficacy over time, and cognitive and psychomotor impairment. New benzodiazepine users commonly experience cognitive side-effects including sedation, inattention, and memory problems. In recognition of the risks of using benzodiazepines, they are rarely indicated as a first line treatment, and clinical guidelines suggest that when needed they are used for the shortest duration possible and at the lowest dose required. Despite this, there is evidence that benzodiazepine use still regularly occurs for extended durations and at high dosages within Australia. Most of the research to date has examined once-off or short duration benzodiazepine use in young, healthy, benzodiazepine-na‚àövòve individuals ‚Äö- a group far removed from the usual benzodiazepine using population who are more often older, have a variety of health conditions, and have used benzodiazepines regularly for an extended period of time. The current study aimed to overcome some of these gaps in the literature by examining benzodiazepine use among existing consumers, as it naturally occurs in the Australian population, specifically focusing on those who use in an ongoing, chronic manner, rather than amongst carefully selected research samples. Understanding the impact of benzodiazepine use on experience of accidents, particularly whilst driving, is an important area of research. This thesis aimed to add to the existing accident literature by examining the influence of benzodiazepine use on a range of different incident severities including: cognitive failures (everyday cognitive slips or errors), minor injuries not requiring medical attention, and major accidents requiring medical attention. Three studies were undertaken: (1) an online, general population survey of chronic benzodiazepine users and their experiences of accidents, injuries, and cognitive failures (n=129), (2) an interview based study examining the unique effects of benzodiazepines on safety incidents in people who inject drugs (n=170) and (3) using the same methods and population group as Study 1, the subjective experiences and perceptions of this group were explored through a qualitative design (n=129). In both Study 1 and Study 3, respondents were divided into three categories of benzodiazepine chronicity; short-term (length of use ‚Äöv¢¬ß year; daily/occasional frequency), intermittent (length of use > year; occasional frequency) and chronic (length of use > year; daily frequency). Reported benzodiazepine use was often daily, of a high dosage, and for an extended period of time. For example, the chronic users in this study had on average a duration of use spanning 8 years, used most days within a month, and had an average diazepam equivalent dosage per month of 900mg. This usage is inconsistent with recommendations from current clinical guidelines. Logistic regression, used in Study 1 showed that chronic, daily, users were at significantly increased risk of general accidents, and retrospective and prospective memory problems, compared to intermittent users. Study 3 aimed to complement the findings of Study 1, by providing information about the self-reported experience, knowledge, and perceptions of chronic benzodiazepine users. Attitudes towards benzodiazepines reported in Study 3 were mixed, although a large proportion of the sample reported negative experiences, such as dependence, withdrawal, and cognitive effects. Side-effects were regularly experienced by the group, and often did not abate, particularly for the most chronic users. Tested knowledge of benzodiazepines in the sample was low, and many respondents stated that they felt they had received inadequate information about the risks associated with benzodiazepine use. Findings from Study 1 and Study 3 indicate that benzodiazepines have a considerable impact on both the subjective and objective safety experiences of chronic users. Study 2 examined the unique impact of benzodiazepine use on cognitive failures, minor injuries, and major accidents, in a group of people who inject drugs (PWID). It is recommended that benzodiazepines are best avoided in PWID, due to the high risk of dependence and additive sedative effects. However, it is known that benzodiazepines are still commonly used by PWID, and this was also evident in Study 2. Despite the range of other substances used by this group, moderate-to-regular benzodiazepine use independently contributed to an increased risk of retrospective memory problems (OR 8.21, 95%CI 1.03-65.41, p=0.047), and major accidents (OR 3.88, 95%CI 1.20-12.50, p=0.023) after controlling for a wide range of confounders. Overall, findings from this thesis suggest that benzodiazepine use in Australia remains inconsistent with clinical guidelines. After controlling for confounding variables, benzodiazepines had a considerable effect on safety in both the general, and a high risk population (PWID). Chronic benzodiazepine users cannot be assumed to be tolerant to the effects of benzodiazepines, and this thesis shows that they continue to experience ongoing, detrimental effects of benzodiazepine use on their safety. It is suggested that there should be more specialised services to assist those who are grappling with benzodiazepine withdrawal and dependence, and importantly to provide alternative treatments to the use of benzodiazepines. It is proposed that the use of a benzodiazepine contract, like those used for opioids, would ensure best practice prescribing occurs, and improve outcomes for both prescribers and patients.