A Stepwise Approach for Preventing Suicide by Lethal Poisoning
Background: Suicide is a global phenomenon and is the 10th leading cause of death in the US. Veterans are more likely to die by suicide than those in the general population. In 2018, the suicide rate for all US veterans was 1.5 times higher than the rate for nonveterans, after adjusting for population differences in age and sex. In light of this disparity, suicide prevention is one of the highest priorities for the US Department of Veterans Affairs (VA). One major goal of the VA suicide prevention strategy is to reduce access to lethal means.
Observations: This article will provide information on medications with high lethality and a stepwise approach for how health care providers may limit lethal medications for patients at high risk for suicide. The first step is to determine suicide risk. More than 90% of those who die by suicide have a psychiatric diagnosis at the time of death. Clinicians can use risk assessment tools, such as the Veterans Health Administration Suicide Prevention Population Risk Identification and Tracking for Exigencies tool. The second step is to identify substances strongly associated with fatalities. According to the American Association of Poison Control Centers, the pharmaceutical classes associated with the largest number of fatalities are stimulants and street drugs, followed by analgesics, cardiovascular agents, antidepressants, antipsychotics, and sedatives/hypnotics. The third step is to consider potential drug-drug interactions, such as the combination of opioids and sedative-hypnotics. Finally, clinicians need to address risks. With high-risk patients it may be preferential to prescribe medications that are less lethal. All patients with a high risk of suicide should receive lethal means counseling.
Conclusions: While firearms continue to be the most lethal means for veteran suicide, intentional poisoning with medications or substances also is a common method for suicide, especially for female veterans. Having knowledge of medications with high lethality and limiting access to these agents can be a successful strategy for reducing suicide deaths.
Step 3: Consider Potential Drug-Drug Interactions
Suicide attempts involving multiple substances carry increased risk. Only 12.1% of all fatal overdoses, according to AAPCC, involved single-substance exposure, whereas 56.3% were attributed to multiple substance exposures.16 It is important for clinicians to be aware of and avoid possibly fatal drug-drug interactions, such as the combination of opioids and sedative-hypnotics, like BZDs, which can lead to fatal respiratory depression. Clinicians also should be aware of a patient’s history of illicit opioid and alcohol use before prescribing opioids and BZDs. Clinicians can use various online databases to detect potential drug-drug interactions.
Step 4: Address Risks
If a patient is deemed to be at high risk for suicide, but it is not imminent and the patient will be managed as an outpatient, then it may be preferential to prescribe medications that are less lethal, such as SSRIs, instead of TCAs or MAOIs. If a potentially lethal medication is indicated, such as lithium or clozapine, both of which have been found to reduce suicidal behavior, then dispensing a limited quantity of pills and having more frequent follow-up visits are some ways to lessen risk.24,25 A clinical pearl published in Current Psychiatry provided an equation to determine the lethality of a 30-day supply of medications.26 This equation uses lethal dose 50 (LD50), which is the dose of a medication that results in the death of 50% of the animals used in a controlled experiment, and the maximum daily dose of the medication (D) to find the human equivalent dose (HED) relative lethality. The HED relative lethality calculation may help prescribers determine which medications should have a limited quantity dispensed to patients at risk of medication-related suicide. Any value for the HED relative lethality that is > 100% is considered a lethal dose for humans. Therefore, it would be appropriate to avoid or limit the quantity of medications with a HED relative lethality > 100%. Table 4 lists the psychotropic agents with the highest relative lethality for a 30-day supply. The psychotropic agents with the lowest HED relative lethality are SSRIs: desvenlafaxine, mirtazapine, topiramate, and aripiprazole.26
Limiting drugs with a narrow therapeutic index should be considered when aiming to reduce the risk of medication-related suicide. These drugs present a high risk in the event of an overdose. Clinicians can monitor the levels of lithium, clozapine, or TCAs to ensure that a patient is taking the medication as prescribed rather than stockpiling it at home. If the patient is in a monitored setting, such as a partial hospital program or intensive outpatient program, then the medication can be given while under direct observation.
Clinicians should obtain an accurate and detailed medication and illicit drug use history from patients. It also is important to review the prescription drug monitoring program to limit access to potentially lethal combinations of medications.27 Clinicians can additionally employ risk mitigation strategies (eg, providing naloxone kits) for patients who are prescribed or abuse opioids.
Finally, all patients with a high risk of suicide should receive lethal means counseling, which involves first determining whether patients have access to lethal means, such as firearms or medications with high lethality, then limiting their access to these lethal means. This includes advising patients and family members to safely dispose medications that are no longer in use and in some cases recommending that a family member keep medications locked and dispense them on a daily basis.
Conclusions
Suicide is a major public health concern that affects tens of thousands of Americans annually. Furthermore, veterans are more likely to die by suicide than those in the general population. Firearms continue to be the most lethal means for suicide. However, intentional poisoning with medications or substances also is a common method for suicide, especially in female veterans. Having knowledge of medications with high lethality and limiting access to these agents can be a successful strategy for reducing suicide deaths.
