Mortality, causes of death and health status among methamphetamine users

Abstract

This study examines causes of death, years of life lost, and health and drug use characteristics associated with mortality over an 8–10 year period in a sample of methamphetamine (MA) users who had and had not received substance use disorder treatment (N=563). Decedents reported initiating their MA use for different reasons than surviving MA users, and some of these differences varied by treatment status. Study findings provide additional detail on long-term health and mortality outcomes in a diverse sample of MA users, which may inform public health strategies targeting the comparable and divergent needs of treated and untreated populations.

Introduction

Research indicates stimulant use is associated with a range of adverse individual and societal consequences including high rates of morbidity and mortality;^1–4 and even with reductions in drug use severity, users show little improvement in physical health over time, underscoring the potential long-term harm of these substances.⁵ While individuals with methamphetamine (MA) use disorders have been shown to exhibit a lower mortality rate than those with opioid use disorders, studies have shown inconsistent results regarding mortality risk for MA users as compared with cocaine users.^6,7 A study by Kaye et al.⁸ indicates that when MA is combined with alcohol, cocaine or opioids, toxicity and stress on the cardiovascular system is increased; accordingly, MA is often detected in combination with other drugs at autopsy.

Among substance users generally and MA users specifically, mental health problems have been associated with greater mortality risk. For example, a long-term follow up study found 24% of drug users admitted for detoxification in Sweden were dead at 15-year follow-up, and greater psychiatric severity at the 5-year follow-up was predictive of mortality. ⁹ Likewise, Kalechstein et al.¹⁰ showed that MA-dependent arrestees were more likely than non-MA-dependent arrestees to report a syndrome consisting of depression and suicidal ideation and a need for psychiatric services, after controlling for demographic profile, HIV serostatus, and history of other substance dependence.

Several external (e.g., overdose, homicide) and disease-related (e.g., cardiovascular, HIV/AIDS) causes of death have been reported to be prevalent among MA and other substance users.^{1, 11} Among young drug offenders in Taiwan, accidents, suicide and circulatory diseases were the leading causes of death.¹¹ A 2007 follow-up study of 1,116 Thai MA users treated in 2001–02 for MA-psychosis found that 8.2% had died, primarily from suicide, accidents or AIDS.¹² Karch et al (1999)¹³ found a strong association between MA use and cardiac enlargement and higher rates of coronary artery disease, myocardial fibrosis, and HIV infection as cause of death in MA users than drug-free controls. Accidents and suicide were the most common cause of death among young illicit drug users (age 15–24 years) in Stockholm, and cardiovascular disease and tumors were most common among older users (age 55 and older); death because of an accident was especially common among persons who had used stimulants alone or with opiates.¹⁴ Previous research has provided important information on specific demographic, drug use, and physical and mental health characteristics that place many substance users at risk for poor health outcomes and premature death, and these characteristics can be seen as potential targets for intervention.^15,16 However, as noted by Muhuri & Gfroerer,¹⁷ most of the observational studies conducted in the United States examining mortality associated with substance use disorders (SUD) have been limited to treatment populations of drug users; and there is less information on MA use relative to other substances.¹⁸ Describing mortality and morbidity across a broader MA-using population and identifying similarities/differences between treated and un-treated MA users may assist in targeting the needs of a wider diversity of MA users.

Thus the current study examines mortality rates and causes of death over an 8–10 year period, as well as years of life lost, in a sample of MA users that includes both those who had and had not received SUD treatment prior to study recruitment. We further examine potential risk factors associated with decedent status (surviving or confirmed deceased). In a separate analysis among surviving study participants, we examine morbidity and health status an average of 20 years after MA users first began using MA regularly. Providing additional detail on mortality and morbidity among a diverse sample of MA users may help focus public health strategies on a significant problem population.

Methods

Study sample

Overall sample

Data are from a longitudinal study examining long-term patterns of MA use. MA users (N=649) who received SUD treatment (labeled “treated” group in this paper; N=351), and MA users who had never participated in formal SUD treatment (labeled “untreated” group; N=298) were recruited and interviewed for this study. Participants were English or Spanish speaking adults. The treated group was recruited from a stratified (by gender, ethnicity and treatment modality) random sample of 1995–1997 SUD treatment admissions in a large county system; 63% received residential and 37% received outpatient treatment (“treatment-as-usual”). This group was recruited and first interviewed in 1999–2001.¹⁹ In 2001–04, a second interview was conducted with the treated group, and the untreated group was recruited and interviewed. Community approaches were used (in the same county as for the treated group) to recruit the untreated group, including an acquaintance sampling approach, key informants, and extensive outreach to achieve socio-demographic and MA use behavior diversity.

Located sample

In 2009–12, long-term follow-up interviews were conducted; of the original 649 baseline respondents, 87% (N=563) were located and had survival/deceased status identified; these 563 are the basis for analyses in the current paper comparing participants by decedent status at the 2009–12 follow-up. This analysis sample was 60% male; 43% White, 29% Hispanic, 17% African American, 6% multi-racial, 3% Native American and 1% Asian American. The mean age at baseline was 32.5 years (SD=8.5); 31% had less than a high school education, 24% had a high school diploma, and 46% had some education post-high school; 59% had received SUD treatment prior to study recruitment and 41% had not received treatment.

Overall, individuals in this study sample have reported long histories of MA use and criminal involvement, and did not have contact with study staff in approximately eight years. A study by Scott²⁰ indicates sustained addiction often creates chaotic lifestyles that lead to physical and social mobility, alienation from friends and family members, and residential instability that leads to greater contact difficulty during follow-up studies. For similar reasons, we were unable to locate 13% of our sample, despite extensive interviewer training and locator procedures; most of these individuals were unable to provide enough detailed locator information at the previous interview (e.g., due to homelessness, lack of family members’ contact information) to be contacted for a future interview. Analysis of participants who were and were not located at the eight-year follow-up indicate a somewhat larger proportion of those not located were men (18% vs. 5% women; p<.01), untreated at initial interview (22% vs. 5% treated; p<.01), Hispanic (24% vs. 8% African American, 9% white, and 3% multi-racial; p<.01), and without a high school diploma (20% vs. 9% for those with a high school diploma and 11% for those with further education beyond high school; p<.01). No differences were found in whether participants were located by age or employment status.

Interviewed sample

A total of N=460 completed the follow-up interview and provide the subsample for examination of health-related characteristics. In this follow-up subsample 59% were male, 41% White, 30% Hispanic, 17% African American, 7% multi-ethnic, 2% Native American and 2% Asian American. The mean age at the 2009–12 interview was 42.3 years (SD=8.6); 29% had less than a high school education, 26% had a high school diploma, and 45% had some education post-high school; 56% had received SUD treatment prior to study recruitment and 44% had not received treatment. Note also that 38% of the treated sample and 33% of the untreated (at initial interview) sample reported treatment participation during the follow-up period.

Study procedures

Face-to-face interviews were conducted at baseline and follow-up, assessing a comprehensive array of self-reported background and substance use characteristics, as well as detailed life-course data on use of selected substances, related behaviors, and treatment utilization over time using the Natural History Interview.^21,22 The follow-up interviews used the same measures as the baseline 1999–2004 interviews, collecting histories since the earlier interviews, thus extending the length of the life history data an additional eight years for an average of 28 years in duration (since age of first drug use, or age 14). The Institutional Review Board at the University of California, Los Angeles approved this study, and participants provided written informed consent.

Death status and causes of death

Death certificates, including date of death and underlying and multiple causes of death were obtained from the Centers for Disease Control National Death Index (NDI) for deaths occurring after the baseline interview and through 2010. Thirty-three study participants were identified as deceased according to the NDI. For 27 of the 33 cases, a complete match was obtained on full name, social security number, date of birth and demographics. For six cases, study participants matched the NDI data on all characteristics with the exception of social security numbers which were not available; four of these individuals were also reported deceased by persons listed on their locator contact forms (these persons provided dates and/or causes of deaths that were consistent with NDI data). In addition, a newspaper article reported one participant was deceased, and the cause and date of death were consistent with NDI data. An additional 12 participants were reported as deceased in other public records databases and/or were reported as deceased by family members or acquaintances, but no death certificate was obtained due to lack of matching on either name or social security number (n=5), or the death occurred after 2010 (n=7). Causes of death, both underlying and “all cause” (as listed in NDI data), were coded according to the International Classification of Diseases (ICD, 10th revision). Underlying cause of death is defined as (a) the disease or injury which initiated the train of events leading directly to death, or (b) the circumstances of the accident or violence which produced the fatal injury.²³ “All causes” included any significant diseases, conditions, or injuries that contributed to death. Causes of death were grouped into the following categories: cardiovascular disease, human immunodeficiency virus (HIV)/AIDS, drug overdose, cancer, multiple injuries, respiratory disease, homicide, liver disease, hepatitis, alcohol/drug disorder, motor vehicle accident, other infectious disease, and all other causes.

Measures

Socio-demographic characteristics

Age, race/ethnicity, gender and employment in the past 30 days were assessed at the baseline interview.

Physical and mental health

At the baseline interview, respondents were asked to rate their current overall health status (on a five-point scale with response options of poor=1 to excellent=5), and whether they ever had any major health problems that kept them from working, going to school or performing daily activities (responses coded as no=0, yes=1; labeled “major health problem” in this paper). Respondents were also asked whether they had a list of specific health conditions. Respondents were administered the 21-item Beck Depression Inventory;²⁴ higher scores reflect greater depression symptoms (Cronbach’s α for this sample was .90). Respondents were asked whether they had experienced specific mental health problems in the past 30 days that were not a direct result of drug or alcohol use, including serious depression or anxiety that lasted two or more weeks, visual or auditory hallucinations, trouble concentrating, understanding or remembering (i.e., cognitive problems) that lasted two or more weeks, and trouble controlling violent behavior. Respondents were also asked whether they ever seriously considered suicide; MA users who seriously considered suicide were asked whether they ever attempted suicide. Lastly, respondents were asked if they had been prescribed medication for psychiatric reasons in the past 30 days.

Substance use

From the baseline interview, substance use behaviors (most categorized as no/yes) included: past month use of MA, regular use of alcohol to intoxication, regular use of heroin, ever injected any drugs, ever overdosed on any drug to the point of becoming unconscious, and use of cigarettes (smoked in the past month, in the past year but not in the past month, and did not smoke in the past year). In addition, respondents were asked whether any of 11 reasons (listed in Table 1) described why they started using MA, with no/yes choices and an option to specify other reasons.

Table 1.

Demographic, health and drug use characteristics (mean [SD] or percent) reported at baseline interview (1999–2004) by mortality status at 2009–12 follow-up (N=563)

	Surviving n=518	Deceased n=45
Demographics
Age **	32.0 (8.4)	37.5 (8.8)
Gender **
Female	41.5	20.0
Male	58.5	80.0
Race
African American	16.8	20.0
Hispanic	29.3	28.9
White	42.5	42.2
Native American	2.3	6.7
Other or multi-racial	9.1	2.2
Employed	36.4	31.1
Substance abuse treatment status
Never received treatment	41.3	37.8
Received treatment	58.7	62.2
Health variables
Self-reported health status **
Excellent	16.4	15.6
Very good	25.1	15.6
Good	34.4	24.4
Fair	20.3	24.4
Poor	3.9	20.0
Major health problema **	21.7	42.2
Beck depression score *	12.3 (9.5)*	15.4 (10.3)*
Mental health problems in past 30 days
Depression *	13.9	26.7
Anxiety *	12.9	24.4
Hallucinations **	2.5	11.4
Cognitive problems	13.6	22.2
Violent behavior	11.1	8.9
Ever attempted suicide **	25.3	44.4
Prescribed psychiatric medication past 30 days **	9.3	22.2
Drug use variables
Used methamphetamine (MA) in the past 30 days	35.5	46.7
Used alcohol to intoxication regularly	68.5	66.7
Used heroin regularly **	12.4	26.7
Ever injected drugs **	41.3	64.4
Ever overdosed ^	36.5	48.9
Cigarette use *
Smoked in past 30 days	75.2	93.0
Smoked in past year	9.6	2.3
Did not smoke in past year	15.2	4.7
Reasons for initiating MA use
For fun	61.8	48.9
To get high	62.3	60.0
For energy	47.9	42.2
Lose weight **	20.8	4.4
Experiment/curiosity **	62.0	42.2
Escape	31.7	33.3
Stay awake	40.7	37.8
Replace another drug	20.7	22.2
Friends/peers use	57.3	60.0
Work more	19.5	22.2
Better sex	23.4	31.1

^**p<.01;

^*p<.05;

^{^}p<.1.

^aEver had a major health problem that interfered with work or daily activities

Health indicators

Respondents were asked at the 2009–12 follow-up interview to rate their current overall health status on a five-point scale, whether they had any major health problems that kept them from working, going to school or performing daily activities since the last interview, and whether they overdosed on any drug to the point of becoming unconscious. In addition, a comprehensive list of medical conditions and health problems from Centers for Disease Control and Prevention’s National Health Interview Survey (NHIS) was used to assess whether respondents had ever experienced specific conditions, including: high blood pressure, heart disease, cancer (e.g., of the lung, throat, colon), asthma, arthritis, ulcer, frequent headaches/migraines, and several other conditions that were not in the NHIS, including severe dental problems (rotting teeth), HIV, hepatitis C, sexually transmitted diseases (i.e., gonorrhea, syphilis, herpes, chlamydia, other STD), injuries to the back or neck; and gunshot or knife wounds. Health behaviors assessed included regular cigarette smoking, i.e., having smoked more than one pack per week for four or more weeks in a row, categorized by recency (current, former, and never regular smokers). Also, respondents were asked whether they saw or consulted with a medical doctor or other health care professional for a physical health problem in the past year.

Analysis

Frequencies and percentages were calculated for causes of death for participants who had NDI data available (N=33). Years of life lost (YLL) was calculated by gender and treatment status based on the National Vital Statistics Report, 2006 U.S. life tables.²⁵ Standardized mortality ratios (SMR) for males and females were calculated using the indirect method²⁶ and 2010 population statistics by age from National Vital Statistics Report ²⁷; 95% confidence intervals were also calculated.²⁸

Chi square and independent samples t-tests compared baseline demographics, health, mental health, and substance use characteristics by mortality status for the overall sample (N=563). Further exploration (using chi square and t-tests) assessed mortality status differences within treated (n=332) and untreated (n=231) subgroups; these results are reported only for variables in which the untreated and treated groups showed differences by decedent status in health and drug use characteristics, i.e., Beck depression score; past month anxiety and depression; and reasons for initiating MA use.

In addition, percentages were calculated for health status, medical conditions and health behaviors reported at the 2009–12 interview for younger (age 26–44; n=291) and older (age 45–64; n=165) respondents. And z-tests compared these percentages to national rates.²⁹

Results

Mortality

A total of 45 study participants (8.0%) died during the follow-up period between baseline and long-term follow-up interviews (average period of observation 9.1 [SD=1.6] years). No differences were observed by treatment status (p=.644); 7.4% (n=17) of the untreated group, and 8.4% (n=28) of the treated group had died. The most common underlying cause of death was HIV/AIDS; and of all causes, cardiovascular disease was most common (Figure 1). Both external and disease-related causes were reported; eleven MA users died of an underlying external cause, i.e., drug overdose, homicide, motor vehicle accident (10 in the treated group and 1 in the untreated group). In contrast, HIV as an underlying cause of death was reported by 5 in the untreated group and 1 in the treated group. All six decedents who died of a drug overdose were from the treated group; five overdoses were listed as accidental (ICD 10 codes of X41, X42 and X44), and one was listed as undetermined intent (ICD 10 code Y14). Each of these six decedents reported at a previous interview overdosing to the point of loss of consciousness one or more times.

Figure 1.

Underlying and contributing causes of death among methamphetamine users (n=33)*

*ICD 10 Codes: Cardiovascular: I120, I250, I251, I429, I469, I517, I739; HIV: B203, B205, B207, B208, B238, B24; Drug overdose: T401, T436, T509, X41, X42, X44, Y14; Cancer: C029, C220, C541, C786, C859, C920; Multiple injuries: S019, S119, S299, S619, T019, T07, T091, T141, T149, Y350, Y354; Respiratory: J189, J439, J440, J81, J969, R092; Homicide: X95, X99; Alcohol/drug disorder: F101, F102, F149; Liver disease: K709, K729, K760, K767; Hepatitis: B171, B182; Motor vehicle accident: V031, V435; Infection: A410, A419, B59; Other: D649, D65, E669, E872, K811, M919, N19, R568.

The average age at death was 44.6 (SD = 9.0). Deceased MA users in this sample had an average of 34.7 (SD=8.9) years of life lost (YLL); men had an average of 33.3 (SD=8.6) YLL, and women 39.9 (SD=8.3) YLL. The untreated group had an average of 32.5 (9.0) YLL, and the treated group 36.1 (SD=8.7) YLL. The standardized mortality for men (for the sample as a whole) was 27.8 (95% confidence interval 19.5 – 38.4) and for women 21.3 (9.7 – 40.4).

Characteristics associated with mortality

As shown in Table 1, several demographic, health and drug use characteristics were associated with mortality for the sample overall. Decedents were older and had a higher percentage of men than surviving study participants, and had higher rates of hallucinations and suicide attempts than survivors. Overall, decedents had higher rates of depression and anxiety and higher Beck depression scores than survivors. Note, however, analyses within treatment status subgroups indicated that these findings apply only to the treated group. In the untreated group, decedents’ rates of depression (17.6%) and anxiety (17.6%) were similar to survivors (15.9%, 17.3%, respectively; results not shown in Table 1). In contrast, in the treated group, 32.1% of decedents reported depression and 28.6% reported anxiety problems, compared to 12.5% and 9.9% of survivors, respectively (p<.01). In the untreated group, decedents had a mean Beck depression score of 12.9 (SD=9.7) compared to 14.4 (SD=10.0) among survivors (p=.557); conversely, in the treated group, decedents had significantly higher mean scores than survivors (16.9 [SD=10.6] versus 10.9 [SD=8.8]; p<.01).

Overall, regular heroin and injection drug use were associated with mortality. Higher rates of survivors than decedents reported using MA to experiment and to lose weight; these differences were found for the sample overall (Table 1) and within both treated and untreated subgroups (results not shown). However, for several reasons for initiating MA use, there were differences by treatment status; consequently, separate analyses by treatment status were conducted. In the untreated group, more decedents initiated MA use for better sex compared to survivors (52.9% versus 18.3%; p<.05); likewise, more decedents than survivors used MA to replace another drug (47.1% versus 18.3%; p<.01). In the treated group, no difference was observed in whether survivors initiated use for better sex (19.7%) compared to decedents (17.9%; p=.842), and decedents were somewhat less likely to use MA to replace another drug compared to survivors (7.1% versus 22.4%; p=.058).

To further explore possible sexual risk and health consequences in the untreated subgroup, we examined whether initiation of MA use for better sex differed by treatment status, and as an indicator of potentially higher sexual risk behavior, whether those who initiated MA for better sex had higher rates of STDs by treatment status. Results indicate that significantly more MA users in the untreated compared to treated group started using MA for better sex (30.3% vs. 19.6%, p<.01). For the treated group, rates of STDs were somewhat high for those who initiated use for better sex (28.1%) as well as those who initiated use for other reasons (21.1%; p=.229); for the untreated group, the rate of STDs was significantly higher for those who initiated use for better sex (34.3%) compared to those who did not (21.1%; p<.05).

Health status at 2009–12 follow-up

Health variables reported at the 2009–12 follow-up interview are shown in Table 2 for younger and older age groups with reference to rates from the 2010 NHIS when available. A greater proportion of both younger and older MA users reported being in fair or poor health compared to their counterparts in the NHIS sample. Rates of heart disease and hypertension were somewhat higher in the MA using sample than the NHIS sample. MA users appear to have rates similar to the NHIS sample of past-year consultation with health care professionals.

Table 2.

Percent reporting health status and health behaviors by age group among methamphetamine (MA) users at 2009–12 follow-up compared to the 2010 National Health Interview Survey (NHIS) sample

	Younger Age Group (18–44)		Older Age Group (45–64)
	MA users N=291	NHIS sample N=110,615	MA users N=165	NHIS sample N=80,198
Self-reported health status
Excellent/very good	32.0 a	70.2 (0.52) a	21.2 b	55.1 (0.67) b
Good	35.1 a	23.3 (0.47) a	31.5	28.5 (0.56)
Fair/poor	33.0 a	6.4 (0.26) a	47.2 b	16.4 (0.48) b
Health conditions
Heart disease	10.0 a	4.4 (0.23) a	21.8 b	13.2 (0.43) b
Hypertension	16.2 a	9.3 (0.31) a	38.2	34.4 (0.60)
Cancer	3.4	2.2 (0.15)	6.7	9.9 (0.37)
Frequent headaches, migraines	16.8	20.4 (0.45)	17.6	15.6 (0.44)
Diabetes	4.1	2.8 (0.17)	15.8	12.3 (0.39)
Asthma	18.2 a	13.6 (0.38) a	9.1	12.1 (0.43)
Ulcer	6.5	4.2 (0.22)	9.1	8.0 (0.32)
Arthritis	13.1 a	7.1 (0.28) a	27.9	30.3 (0.59)
Health Behaviors
Current smoker	59.5 a	21.5 (0.49) a	56.4 b	21.1 (0.52) b
Former smoker	16.5	12.7 (0.35)	18.8	25.6 (0.56)
Never smoked	24.4 a	65.8 (0.55) a	25.5 b	53.3 (0.67) b
Did not consult with health care professional in past 12 months	22.9	27.1 (0.50)	20.6	15.9 (0.48)
Other health conditions/indicators
HIV	3.1	--	7.3	--
Sexually transmitted disease	18.9	--	26.7	--
Hepatitis C	13.1	--	26.1	--
Back/neck injury	18.2	--	28.5	--
Severe dental disease	24.7	--	24.2	--
Gunshot/knife wound	24.4	--	20.0	--
Ever overdosed	49.8	--	47.3	--
Major health  problem^^	27.5	--	49.1	--

^az score indicates meth users differed from NHIS sample at p<.05 in younger age group.

^bz score indicates meth users differed from NHIS sample at p<.05 in older age group.

^*Standard errors reported with NHIS percents.

--NHIS data not available for these conditions.

^{^^}Major health problem that interfered with work or daily activities since last interview.

Analyses of health conditions not reported in the NHIS, but often observed in substance-using populations, indicate commonly reported medical conditions in the MA-using sample included severe dental disease (24% and 25% for younger and older subgroups), gunshot/knife wound (20–24%), and STDs (19–27%). Almost half (of both younger and older subgroups) reported taking an overdose of drugs one or more times.

Discussion

Our study followed a sample of treated and untreated MA users for an average of 9 years after their baseline interview, and found the crude death rate (8%) within the range of rates reported in previous studies of stimulant or methamphetamine users.^12,30–32 The standardized mortality ratio for females was similar to that in Kuo and colleagues ³¹ but greater than that reported in Hser and colleagues for female methamphetamine users³⁰; for males in the current study, the SMR was greater than that reported by Kuo and colleagues.³¹

The leading causes of death in our study were HIV, cardiovascular disease, overdose, cancer and homicide. These deaths were considerably premature, with an average of 34.7 years-of-life lost. Risk factors (from baseline interview) for premature death included older age, male gender, self-reported poorer health status and having a major health problem, higher depressive symptom scores, recent mental health problems (including depression, anxiety, and hallucinations), attempted suicide, regular heroin use, injection drug use, and current smoking.

Nearly half of the decedents in this study had attempted suicide, and 11% experienced hallucinations, suggesting treated and untreated MA users with these mental health problems may be at a heightened risk for premature death. Previous studies with treatment samples indicate a relationship between MA use, psychiatric problems and poor health outcomes, for example, individuals with MA-induced psychosis experienced several relapses of psychotic symptoms, suicidality and premature death.¹² Other studies show MA users had higher rates of psychiatric diagnoses and use of psychiatric medications than cocaine users,³³ and suffered a range of harms associated with the effects of MA, including depression, anxiety and hallucinatory experiences.³⁴ In the treated group, higher rates of anxiety and depression problems were associated with mortality, but this finding was not observed for the untreated group. However, most of the untreated group was using MA at the time mental health problems were assessed, and as found in previous research³⁵ MA use may have masked symptoms of underlying anxiety and depression.

Our findings indicate a common cause of death for the treated group was drug overdose, and each of these decedents whose cause of death was overdose previously experienced one or more non-fatal overdoses. Non-fatal overdose was common in this study sample as well, supporting the need for greater overdose prevention and education efforts; such efforts conducted within healthcare and community settings, and treatment settings in particular, may be indicated. This finding is consistent with a national study by Bohnert et al.³⁶ indicating stimulant use disorders represent one of the strongest risk factors for accidental overdose deaths. In addition, from 2003–2009, accidental and suicidal overdoses have increased in the United States by 46.9% and 9.9%, respectively, suggesting prevention efforts, especially for unintentional overdose mortalities are needed.³⁷

Injection drug use (IDU) and heroin use in this sample of MA users were also associated with mortality, and are important behaviors to target for intervention, given IDU and heroin use are common among MA users.^{19, 35} A study of injection drug users in Vancouver found MA was the drug most strongly associated with overdose in their sample, and of those who overdosed, 62% were unaware of the drug’s potency, and 65% were taking other drugs at the time of overdosing.³⁸ Frequent MA injection was also reported to be an independent risk factor for emergency department (ED) utilization, with the most common ED presentations being related to substance dependence, overdose and psychiatric diagnoses.³⁹

Regarding specific reasons for initiating MA use among the untreated MA users, our findings indicate higher mortality was associated with initiating MA use to replace another drug; this finding was not observed for the treated group. It is possible that untreated MA users who were experiencing serious mental health problems or negative effects from another substance attempted to manage these problems/effects by replacing that substance with MA, which may result in poor outcomes including premature death. A previous study indicates untreated MA users were less likely to be covered by health insurance compared to treated MA users,⁴⁰ thus may have less access to health care services needed to address substance-related problems.

Another distinction between the treated and untreated groups was that more MA users in the untreated group initiated MA use for better sex, and those in the untreated group who identified this reason had a higher rate of mortality. Although research with larger sample sizes is needed, our findings suggest HIV as an underlying cause of death may be more common in untreated compared treated MA users. Moreover, in the untreated group, a significantly higher rate of STDs was observed for those who initiated MA use for better sex compared to those who initiated their use for other reasons. Taken together, these findings suggest untreated MA users who initiate their MA use for better sex may engage in more sexual risk behaviors and be at greater risk for premature death relative to MA users who initiate their use for better sex, but obtain treatment. Findings in this sample indicate individuals who initiated MA use for sexual enhancement were less likely to obtain treatment, however, further study with larger samples of decedents and controlling for length of lifetime MA use is needed. Similarly, the results of a literature review show that MA users face heightened HIV risk compared to users of other drugs, and the effect of MA may lead an individual to engage in risk behaviors that he or she otherwise would not.⁴¹ Further research is also needed on the impact of SUD treatment and sexual risk reduction interventions among a broader diversity of individuals who use MA for sexual reasons, and how to effectively engage them in treatment.

Several health conditions and experiences reported at the follow-up interview overlap with causes of death among MA users, including hypertension, cardiovascular disease, gunshot/knife injuries and non-fatal overdoses. These findings are consistent with previous studies indicating specific external and disease-related conditions are common in MA users.^1,3,42 While MA users appear to differ from their counterparts in the general population on overall health status, tobacco use and heart disease, MA users consulted with healthcare professionals at roughly similar rates as seen in the general population, suggesting health care providers, possibly in primary or urgent care settings, may encounter MA users who they could potentially engage in screening and intervention. Our findings suggest there is a need to assist MA users in accessing appropriate health services, and to enhance the capacity of primary health care services to meet the demands associated with MA use. Emergency departments (ED) may be a targeting vector for identifying MA users for health and substance use interventions and as a venue for brief interventions, as ED visits resulting from medical and psychiatric complications of MA abuse have increased in recent years.³

Results of this study should be interpreted within several constraints. The sample was selected from one county in California, therefore findings from this study may not be applicable to MA users in other geographic regions. Interview data were self-reported and retrospective, thus may be affected by respondents’ ability to remember and accurately report information; however, interview procedures were designed to facilitate recall.²² The number of decedents was small, such that power for detecting differences between decedents and those surviving was limited. In addition, while the NHIS sample was adjusted to the U.S. standard population, our sample of MA users was not representative of U.S. estimates in terms of age, gender and ethnicity, therefore provides only approximate comparisons across the younger and older age groups. Differences between decedents and those surviving could be assessed only for characteristics available from the initial interview since follow-up interviews with detailed history during follow-up were not available for decedents. Thus, time-varying covariates (e.g., treatment status change after initial interview, continuing substance use and/or recovery, comorbidities) could not be included for decedents. Future studies with more frequent follow-up interviews could provide these data (up to time of death or follow-up interview) for more refined analyses.

In terms of misclassification of surviving and deceased study participants, we have attempted to address this limitation by excluding from the analyses participants who could not be confirmed as deceased or surviving (n=86). The provision of SUD treatment for the treated sample was confirmed by both self-report and treatment system records, however, the untreated sample was classified as never having received SUD treatment at the time of their baseline interview based on self-report only and as noted above, may be affected by respondents’ ability to remember and accurately report this information. Regarding loss to follow-up bias, Hispanics, men, those who had not receive treatment prior to recruitment, and individuals with lower levels of education comprised a significant proportion of the 86 individuals who could not be located. Although most of these participants could not provide adequate locator information for follow-up interviews, it was important to include them in the baseline interviews in order to capture a more accurate picture of MA use in the community sample. In addition, 76% to 82% of these subsamples were located, providing data on under-studied MA-using populations. Further study of long-term health and mortality consequences in these MA using populations, particularly Hispanic men, is warranted.

The current study adds new morbidity and mortality information for MA users who have never received SUD treatment relative to those who received treatment, and examines a comprehensive set of potential risk factors including health status, mental health problems and motivations for initiating MA use. A subset of MA users, including users who do not access treatment but initiate their use for better sex or to replace another drug may require innovative outreach and intervention efforts to address their health and treatment needs. Overall, findings indicate both treated and untreated MA users are at heighted risk for poor health outcomes and premature death, and risk factors differ in some respects by treatment status. These risks should be considered when developing health care strategies and resources to improve health outcomes. Specific subgroups of MA users may benefit from interventions that focus on medical and mental health care needs, prevention of drug overdose, and sexual and injection risk behaviors. Additional study of mortality and causes of death by treatment status may further elucidate whether the needs of treatment clients differ from those who do not obtain treatment.