Standard Death Certificates Versus Enhanced Surveillance to Identify Heroin Overdose–Related Deaths

Abstract

Objectives. To compare 2 approaches to identifying heroin-related deaths in cases of overdose: standard death certificates and enhanced surveillance.

Methods. We reviewed Maryland death certificates from 2012 to 2015 in cases of overdose to determine specific mentions of heroin. Counts were compared with estimates obtained through an enhanced surveillance approach that included a protocol considering cause of death, toxicology, and scene investigation findings.

Results. Death certificates identified 1130 heroin-related deaths. Enhanced surveillance identified 2182 cases, nearly double the number found through the standard approach. The major factors supporting enhanced surveillance in identifying cases were the presence of morphine, either alone or in combination with quinine, and scene investigation information suggesting heroin use.

Conclusions. Death certificates, the primary source of state and national data on overdose deaths, may underestimate the contribution of heroin to drug-related mortality. Enhanced surveillance efforts should be considered to allow a better understanding of the contribution of heroin to the overdose crisis.

Public Health Implications. If enhanced surveillance can be incorporated into the death certificate process, national data on overdoses may better reflect the contribution of heroin to the opioid crisis.

According to the Centers for Disease Control and Prevention, 12 989 heroin-related deaths occurred in the United States in 2015, more than a 4-fold increase over the 2010 figure of 3036.¹ These figures are based on information reported on death certificates.

Death certificates, from which state and national death statistics are derived, are the primary source of information on counts of drug overdose deaths. If a death is to be identified as heroin related on a death certificate, the medical certifier who provides cause of death information must include the term “heroin” in the cause of death section of the certificate. There are several reasons why this may not occur, even in the case of a death that is likely to be heroin related.

First, the medical certifier may not document the specific substance that caused the death, instead listing “narcotic intoxication,” “drug overdose,” or another nonspecific cause of death.^2–4 Second, a number of factors may make it difficult to identify a death as heroin related, including time elapsed between drug use and specimen collection, variations in routes of drug administration, chronicity of use, and quality of analysis. Third, because the half life of heroin is extremely short, it is rarely detected in body fluids. Morphine and 6-monacetylmorphine are breakdown products of heroin and are far more likely to be present than heroin by the time of specimen analysis; as a result, “morphine intoxication” may be listed as the cause of death even if a review of external information would suggest that heroin is likely to have been the cause.^3,5,6

An alternative approach to standard death certificate reporting is enhanced surveillance, in which a specific protocol is deployed to best assess whether heroin is a contributing factor in overdose deaths. In such a protocol, factors including toxicology findings, history of heroin use, and the presence of heroin or drug paraphernalia at the scene could routinely be considered.

It has been established that some heroin-related deaths are not counted in state and national statistics.^3,4 However, the extent of the potential undercount has not been determined. Our goal was to assess the degree of undercount in one state by comparing counts of heroin-related deaths obtained through the standard death certificate approach with estimates obtained through enhanced surveillance.

METHODS

In Maryland, the Vital Statistics Administration of the Department of Health is responsible for compiling and reporting on drug overdose deaths occurring in the state. The major source of overdose data is the Office of the Chief Medical Examiner (OCME), which is required to investigate all deaths occurring in the state that result from violence, suicide, or casualty or that take place in a suspicious, unexpected, or unusual manner. A critical goal of the investigation is to determine the manner and cause of death and report this information on the death certificate. Cause of death information represents the medical certifier’s best medical opinion. Consequently, the information provided may vary among certifiers.

As noted, we compared 2 approaches to assessing the contribution of heroin to the total number of overdose deaths: standard death certificates and enhanced surveillance. In the standard death certificate approach, cases were identified by reviewing the cause of death section of the death certificate to identify records that included the term “heroin.” Cause of death information for the period 2012 to 2015 was obtained from records provided by OCME.

The enhanced surveillance approach was developed through a cooperative effort involving staff of the Vital Statistics Administration, OCME, the Maryland Poison Center, and the Department of Health’s Behavioral Health Administration. To determine whether any likely heroin-related death records were missing the term “heroin” in the cause of death section and were therefore not counted in the standard death certificate approach, we obtained all records from OCME that included any of the following cause of death terms: poisoning, intoxication, toxicity, inhalation, ingestion, overdose, exposure, chemical, use, combined effects, combined toxic effects, or effects.⁷ We reviewed cause of death information, toxicology results, and scene investigation notes for each case to identify deaths that were likely to be heroin related.

In the enhanced surveillance approach, an overdose death was classified as heroin related if it met one or more of the following criteria: (1) heroin was listed in the cause of death section of the death certificate, (2) the toxicology screen showed a positive result for 6-monacetylmorphine, (3) the toxicology screen showed positive results for quinine in combination with either morphine or free morphine, or (4) the cause of death section listed morphine or did not specify a substance (e.g., “narcotic intoxication”) and the scene investigation notes suggested that heroin was likely to have been involved in the death.

Because quinine is frequently added to heroin to increase volume, enhance effects, or mask the quality of the drug, a death was likely to be heroin related if both quinine and morphine or free morphine were found in body fluids.^8,9 With respect to the use of scene investigation notes, examples of the types of information that would strongly suggest the involvement of heroin are reports that the decedent was a known heroin user and was found with drug paraphernalia and reports that heroin use had been witnessed on the date of death. A death was not classified as heroin related if a review of the scene investigation notes suggested that a prescription form of morphine may have been responsible for the death.

RESULTS

The standard death certificate approach to identifying heroin-related deaths detected 1130 deaths between 2012 and 2015. The enhanced surveillance approach identified 2182 heroin-related deaths, nearly double the number. Approximately 29% of all Maryland overdose deaths were found to be heroin related according to the standard death certificate approach, as compared with 55.1% according to enhanced surveillance. The total number of overdose deaths, the total number of heroin-related deaths, and the percentage of heroin-related deaths identified through both methods increased during the study years (Table 1).

TABLE 1—

Total Overdose Deaths and Heroin-Related Deaths According to Approach Used for Identification of Heroin Deaths: Maryland, 2012–2015

Year	Total Overdose Deaths, No.	Heroin-Related Deaths by Approach Used for Identification
		Standard Death Certificate, No. (% Total Deaths)	Enhanced Surveillance, No. (% Total Deaths)
2012	799	179 (22.4)	392 (49.1)
2013	858	221 (25.8)	464 (54.1)
2014	1041	309 (29.7)	578 (55.5)
2015	1259	421 (33.4)	748 (59.4)
Total	3957	1130 (28.6)	2182 (55.1)

The 1052 additional records identified through enhanced surveillance were identified through a combination of sources (Table 2). Toxicology results showed that 136 records indicated the presence of 6-monoacetymorphine, 892 indicated the presence of both morphine and quinine, and 998 indicated the presence of morphine or free morphine. In addition, 804 records listed morphine, either alone or in combination with other substances, as the cause of death. All records that cited morphine included supporting evidence from scene investigation notes that the death was likely to be heroin related. Because some deaths were identified through more than one source, counts of individual sources do not sum to the total.

TABLE 2—

Source of Identification of Heroin-Related Records: Maryland, 2012–2015

Source of Identification of Record	No. of Deaths
Overall total	2182
Standard surveillancea
Total standard surveillance	1130
Enhanced surveillance
Total enhanced surveillance	1052b
Toxicology findings
Presence of 6-monoacetylmorphine	136
Presence of both morphine and quinine	892
Presence of morphine or free morphine and supporting evidence from scene investigation	998
Morphine listed as a cause of death on death certificate and supporting evidence from scene investigation	1042

^aHeroin listed as cause of death on death certificate.

^bCounts of subcategories do not sum to the total because some deaths were identified through more than one source.

In comparison with death certificates, the enhanced surveillance approach identified more heroin-related deaths for all age groups, for all racial/ethnic groups, and for both men and women (Table 3). Death certificates of young decedents were most likely to reference heroin. The percentage of overdose death records reporting heroin was 58.2% for individuals younger than 25 years and declined with age, reaching a low of 41.9% for individuals 55 years or older. In terms of race/ethnicity and gender, heroin was reported on the death records of more non-Hispanic Whites (53.5%) than Blacks (47.0%) and on the records of more men (56.8%) than women (35.1%). The percentage of records that identified heroin was particularly low for Black women (25.9%). Although heroin was reported on a relatively high percentage of death records of Hispanic men (77.3%), it was not reported on the records of any Hispanic women.

TABLE 3—

Heroin-Related Deaths Occurring in Maryland by Source of Identification and Selected Demographic Characteristics, 2012–2015

Characteristic	Totala	Identified Through Standard Surveillanceb
		No.	% (95% CI)
Total	2182	1130	51.8 (49.7, 53.9)
Year of death
2012	392	179	45.7 (40.7, 50.6)
2013	464	221	47.6 (43.1, 52.2)
2014	578	309	53.5 (49.4, 57.5)
2015	748	421	56.3 (52.7, 59.8)
Age group, y
<25	237	138	58.2 (51.9, 64.5)
25–34	566	328	58.0 (53.9, 62.0)
35–44	447	244	54.6 (50.0, 59.2)
45–54	592	278	47.0 (42.9, 51.0)
≥55	339	142	41.9 (36.6, 47.1)
Race/ethnicity
Non-Hispanic White	1505	805	53.5 (51.0, 56.0)
Non-Hispanic Black	623	293	47.0 (43.1, 50.9)
Hispanic	26	17	65.4 (47.1, 83.7)
Other	25	14	56.0 (36.5, 75.5)
Gender
Male	1680	954	56.8 (54.4, 59.2)
Female	501	176	35.1 (30.9, 39.3)
Race/ethnicity and gender
Non-Hispanic White, male	1147	664	57.9 (55.0, 60.7)
Non-Hispanic White, female	358	141	39.4 (34.3, 44.4)
Non-Hispanic Black, male	488	258	52.9 (48.4, 57.3)
Non-Hispanic Black, female	135	35	25.9 (18.5, 33.3)
Hispanic, male	22	17	77.3 (59.8, 94.8)
Hispanic, female	4	0	0.0

Note. CI = confidence interval.

^aIncludes deaths identified through standard and enhanced surveillance approaches combined; excludes 1 decedent of unknown age, 3 decedents of unknown race, and 1 decedent of unknown gender.

^bIncludes deaths identified through cause of death information provided on death certificates.

The majority of records that did not specify heroin instead listed morphine, either alone or in combination with other substances, as the cause of death (n = 804; 76.4%). A total of 193 records (18.3%) did not list a specific substance but instead identified the cause of death as, for example, narcotic or opioid intoxication. The remaining 55 records (5.2%) identified a substance other than heroin as the cause of death. The percentage of records that reported heroin increased over the study period, from 45.7% in 2012 to 56.3% in 2015 (Table 3).

DISCUSSION

In Maryland, the Office of the Chief Medical Examiner routinely conducts investigations and assigns the cause of death on death certificates on the basis of best medical opinions. It appears that this approach may be conservative in attributing the cause of death to heroin use, as an enhanced surveillance approach identified nearly double the number of likely heroin-related deaths.

Effective public health policies and programs depend on accurate and reliable data, and our study suggests that in Maryland death certificate data alone undercount deaths associated with heroin. This finding has national implications given that national counts of heroin-related deaths are based on death certificate information reported to the Centers for Disease Control and Prevention by state vital records offices. The degree to which national counts of heroin-related deaths may be underestimated is unclear owing to potential state variation in identification and recording of these deaths.

Overdose death data from 2010 showed substantial variation among 11 jurisdictions in the degree to which drug overdose deaths were associated with “other and unspecified drugs” and “other and unspecified narcotics” rather than with a specific substance. The US age-adjusted overdose death rate associated with other and unspecified drugs was 3.1 per 100 000 population and ranged from 0.2 to 7.4 for the 11 jurisdictions. In the case of deaths associated with other and unspecified narcotics, the US figure was 0.8 per 100 000 population and ranged from 0.5 to 4.8.⁴

Our investigation showed that the impact of enhanced surveillance varies by demographic group, such that death certificate records may underestimate the problem of heroin-related deaths among older individuals, women, and Blacks. Although national and Maryland death certificate data show that the number of heroin-related deaths is highest among individuals 25 to 34 years old and then declines with age, this was not the trend in Maryland with enhanced surveillance; the greatest number of deaths occurred in the 45- to 54-year age group, and a large number occurred among individuals aged 55 years or older. Similarly, with enhanced surveillance, the number of heroin-related deaths was substantially higher among women, particularly Black and Hispanic women, than death record information alone would indicate.

Why does this matter? Policy responses to prescription opioid–related deaths are not the same as those for illicit drugs, including heroin. The former are generally focused on improving the prescribing of opioids for pain and the use of prescription drug monitoring programs; the latter are more likely to include harm reduction approaches such as syringe service programs and access to treatment in such settings as jails and emergency departments. Improved surveillance can help local health authorities better understand the nature of the opioid crisis in their jurisdictions and allocate resources for the most appropriate solutions.

National conversation concerning the need for more standardized criteria is growing. According to members of the Substance Abuse and Mental Health Services Administration and professional societies including the National Association of Medical Examiners and the American College of Medical Toxicology, there is a need for a standardized methodology in the identification and documentation of opioid-related deaths to improve accuracy of counts at the state and, therefore, national level.^10,11 National experts have identified a need for greater standardization in scene investigation, toxicological testing and analysis, case definitions, and determination and documentation of causality.^10,11

In documenting cause of death, experts from the Substance Abuse and Mental Health Services Administration recommend that all drugs determined to be physiologically significant in causing death be listed on the death certificate and that the parent drug rather than the drug metabolite be listed when supported by toxicological testing or scene investigation findings (e.g., attributing morphine to the breakdown product of heroin). Experts also recommend greater clarity in the language used on the cause of death field of the death certificate; that is, terms such as toxicity, toxic effects, intoxication, and poisoning should be used rather than “overdose” and “use,” which lack precise meaning. With respect to toxicological testing, they suggest that toxicological measurements be evaluated in terms of their ability to distinguish between chronic and acute drug use to allow for better interpretation of drug concentration data.¹²

Implementation of these recommendations is already under way in Maryland, where the percentage of heroin-related deaths that could be identified from death records increased from 45.7% in 2012 to 56.3% in 2015. However, until these recommendations are fully implemented in all states, an enhanced surveillance approach such as that used in Maryland can assist in comprehensively identifying heroin-related deaths. It is critical that medical examiner offices and state vital records offices work together closely to ensure that the information provided on death certificates is as complete and precise as possible. State vital records offices should consider developing a tool to assist medical certifiers in providing the data needed to accurately track drug deaths for all substances. Because medical examiner offices are already collecting most or all of the information needed, it should be possible for them to provide improved cause of death data with limited additional resources.

Limitations

A limitation of our study is that some of the deaths identified through the enhanced surveillance process may not have been heroin-related deaths. For example, a small percentage of deaths for which the cause of death was listed as morphine intoxication may not have been heroin related. However, in each of these cases there was either toxicological or scene investigation information suggesting that the death was heroin related, and thus this percentage is likely to be very small. It is also possible that some of the 55 deaths in which a substance other than heroin or morphine was listed on the death certificate were not heroin-related deaths; the medical certifier may instead have determined that although toxicology or scene investigation notes indicated that heroin was present, it was not directly related to the death. However, given the strong evidence that most of the additional deaths identified were heroin related, the enhanced surveillance approach we used almost certainly provides a more accurate count of heroin-related deaths than the use of death certificate information alone.

Public Health Implications

Deaths from drug overdoses involving heroin have been increasing sharply throughout the United States in recent years, and in Maryland they now exceed the numbers of homicides, suicides, and motor vehicle accidents. Maryland’s challenge reflects the national struggle with overdoses, which have become the leading cause of preventable injury deaths.¹⁰ Recent increases in deaths attributed to diseases of the heart nationally and in Maryland after years of decline^12,13 may suggest that the problem of overdose deaths is even worse than believed given that these increases might represent missed overdose deaths.

The contribution of heroin to drug-related mortality appears to be substantially underestimated when death certificates, the primary source of state and national data on drug-related deaths, are used to count heroin deaths. In Maryland, only about half of all drug-related deaths identified as heroin related through enhanced surveillance would have been identified as heroin related if information provided on death certificates had been used. Other sources of information, such as toxicology results and scene investigation reports, are needed to comprehensively identify these deaths. Efforts must be made to better document the substances involved in a death on death certificates so that these records can be used more effectively to accurately measure the magnitude of the problem of heroin-related deaths, correctly identify groups at increased risk of death, and develop comprehensive strategies to address the devastating consequences of the growing drug epidemic.