A Prospective Observational Cohort Pilot Study of the Association Between Midazolam Use and Delirium in Elderly Endoscopy Patients

Dickson Lee; Fiona Petersen; Maurice Wu; Gwenda Chapman; Melanie Hayman; Kerrilyn Tomkins; Jeremy Fernando

Disclosures

BMC Anesthesiol. 2021;21(53) 

In This Article

Methods

Study Setting

This study was based at Rockhampton Hospital, the largest hospital in regional Central Queensland, Australia. Male and female patients ≥65 years of age undergoing endoscopic procedures between September 2018 and March 2019 were included in the study.

Recruitment

Patients were identified through the National Bowel Cancer Screening Program (NBCSP) and General Practitioner referrals for endoscopy through the Rockhampton Hospital General Surgery Clinic. Consent was obtained through return mail or via face-to-face recruitment at the pre-admission clinic prior to procedure. In all instances, patients were asked to nominate a designated carer to participate in the study and consent was obtained from both parties.

Eligibility Criteria

To be eligible for this study, participants were required to be elderly (> 65 years old) patients undergoing elective endoscopic procedures in the Rockhampton region.

Exclusion criteria included; (a) an inability to consent, (b) pre-existing diagnosis of dementia, (c) non-English speaking carers and (d) patients with no contactable carer. Exclusion of patients with a diagnosis of dementia was to reduce the potential for a significant confounder.

There were several groups of patients who were included to the study initially, but subsequently excluded. These groups are as follows: (a) patients who did not receive midazolam, (b) patients did not undergo an endoscopy, (c) patients or carers who withdrew consent or were unable to be contacted within 24 to 48 h pre and post procedure and (d) patients who had their procedure prior to the administration of the pre-procedure interview. The anaesthetists administering sedation were unaware of whether a patient was enrolled in the study.

Measurement of Delirium

In this study, the Family Confusion Assessment Method (FAM-CAM) was used. This tool is validated for delirium screening and categorically determines the presence or absence of delirium. When compared to the original Confusion Assessment Method (CAM), it has been shown to have a high level of agreement (over 95%).[15] The CAM itself has a sensitivity and specificity to detect delirium of > 90% when validated against psychiatrist diagnosed delirium.[16] Additionally, the FAM-CAM can be administered to any carer (i.e. spouse, family member, friend, etc.) and maintains high fidelity.

The Family Confusion Assessment Method (FAM-CAM) 11 question survey (Appendix 1) was administered over the phone to the patients' carers 24–48 h in advance of their procedure, then 24–48 h after their procedure. By scoring the results of the survey against the 3 required criterion to diagnose delirium, based on the algorithm in Figure 1, patients were identified to have the presence or absence of delirium.

Figure 1.

Family confusion assessment method (FAM-CAM) Algorithm. Patients must score at least one criterion in each column to be diagnosed with delirium

Variables

The possible outcomes of study participants include the presence or absence of delirium based upon the FAM-CAM. All participants must have been exposed to midazolam to be included in the study. Potential confounders exist within the study as follows:

  1. Co-administered anaesthetic agents

  2. Potential for variable depths of anaesthesia

  3. Non-standardised midazolam dosing regimens

Bias

Sources of bias may include the anaesthetists' awareness of the study occurring, and the potential for subjectivity of nominated carers in providing responses to the FAM-CAM. Anaesthetists were not made aware of which patients were participants of the study and patients did not know whether they would receive midazolam, and were subsequently excluded if midazolam was not administered. Standardised clarifications were provided to nominated carers regarding the FAM-CAM questionnaire to assist in improving understanding and quality of responses. Additionally, there is bias in the exclusion of patients with dementia, however, given the known major impact of dementia on the development of delirium, this was identified as an unacceptable confounder and excluded.

Data Collection

Following consent from the participant and their nominated carer after the procedure, information regarding age, and medical co-morbidities were collected from electronic databases. Following the procedure, the Automated Anaesthetic Record Keeper electronic record was accessed to determine whether midazolam was administered, the dosage administered and concurrently administered medications, as well as, height and weight data. Data not found on the electronic system was obtained via chart review.

Ethics

Ethical approval was obtained from the Central Queensland Hospital and Health Service Human Research Ethics Committee (HREC/18/QCQ/30). All participants (patient and carer pairs) required informed written consent. All methods were carried out in accordance with local guidelines and regulations.

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