Addiction Medicine, Article

Prescription opioid misuse among ED patients discharged with opioids

a b s t r a c t

Study objectives: The purposes of this study were to determine the prevalence of prescription Opioid misuse in a cohort of discharged emergency department (ED) patients who received Prescription opioids and to examine factors predictive of misuse.

Methods: This prospective observational study enrolled a sample of ED patients aged 18 to 55 years who were discharged with a prescription opioid. Participants completed surveys at baseline in the ED, then 3 and 30 days later. Follow-up surveys contained questions about opioid use and misuse, including screening questions from the National Epidemiologic Survey on Alcohol and Related Conditions. Patients were categorized as misusers if they (1) self-escalated their dose, (2) obtained additional prescription opioids without a prescription, or (3) used for a reason besides pain.

Results: Of the 85 patients who completed follow-ups, 36 (42%) reported misuse at either 3 or 30 days. There was no difference in demographic variables, pain scores, analgesic treatment, or discharge diagnoses between misusers and nonmisusers. Self-escalation of dose was the most common category of misuse (33/36; 92%). Taking prescription opioids without a doctor’s prescription was reported by 39% (14/36), and taking pain medications for a reason other than pain was reported by 36% (13/36). The presence of disability, chronic pain, preexisting prescription opioid use, oxycodone use, and past 12-month risk of substance abuse were associated with misuse.

Conclusions: Prescription opioid misuse was prevalent among this cohort of ED patients. A heterogeneous mixture of behaviors was captured. Future research should focus on the etiologies of misuse with directed screening and interventions to decrease misuse.

(C) 2014

  1. Introduction

Hydrocodone is now the most commonly prescribed medication in the United States, more than any blood pressure, cholesterol, or diabetes medication [1]. The International Narcotics Board reported that US demand for hydrocodone alone is about 27.4 million grams annually, compared with 3237 g for Britain, France, Germany, and Italy combined [1]. Widespread use and availability of opioids has important negative health and social consequences for both users and the wider public. More than 1 million emergency department (ED) visits per year are directly related to prescription drug misuse and abuse, a figure that has nearly doubled from 2004 to 2009 [2,3]. Even more alarming, the United States has experienced a 5-fold increase in opioid- related deaths since 1970, with most fatalities now related to prescription

? Funding sources: Funding for this study was provided by the Brown University Department of Family Medicine, supported by a grant from the Health Resources and Services Administration.

?? Prior presentations: American College of Emergency Physicians Scientific

Assembly; Seattle, Washington; October 2013.

* Corresponding author. Tel.: +1 401 444 2577; fax: +1 401 444 4307.

E-mail address: [email protected] (F.L. Beaudoin).

opioids [2]. Furthermore, most overdoses occur in patients who were prescribed opioids by a single provider, and a significant proportion of overdose deaths occur in patients prescribed opioids [4].

Prescription opioids are misused by patients when they are used more often or in higher amounts than prescribed, without the prescription of a physician or for reasons other than pain [5-7]. Prescription opioid misuse is an established concern among physicians prescrib- ing opioids for chronic pain in the outpatient setting, with some studies reporting high rates of misuse [8,9].

The prevalence and characteristics of prescription opioid misuse among ED patients who are prescribed opioids is unknown. Given that emergency physicians are one of the top prescribers of prescription opioids [10], it is important to understand the extent of misuse among the ED patient population before we can take steps to implement effective Screening tools and interventions for misuse among ED patients. The primary aim of this study was to determine the prevalence of prescription opioid misuse in a cohort of discharged ED patients who received prescription opioids. Specifically, we aimed to identify the proportion of recruited patients who, based on self-report, misused their prescription opioids at 3 or 30 days after discharge from the ED. Secondarily, we aimed to determine whether demographic and

http://dx.doi.org/10.1016/j.ajem.2014.02.030

0735-6757/(C) 2014

clinical characteristics, as well as history of drug abuse, differed between misusers and nonmisusers or was associated with misuse. Given the role of prescription opioids in providing pain relief and existing concerns about the under-treatment of pain in the ED [11], we also aimed to compare the trajectory of patient’s pain (pain over time) between misusers and nonmisusers.

  1. Materials and methods
    1. Study design, setting, and selection of participants

This was a prospective, observational single-center study con- ducted from January to March 2013. The study was conducted at a large Urban academic ED, a level 1 trauma center with an annual ED census of more than 100000 adult visits per year. The study was approved by the site’s institutional review board.

A consecutive sample of subcritical ED patients, discharged during randomly assigned 8-hour shifts (from 7 AM to 12 AM, 7 d/wk) were assessed for eligibility. Patients were eligible for inclusion if they were aged 18 to 55 years, English speaking, able to provide informed consent, discharged from the ED with an Opioid prescription, and able to participate in follow-up surveys via telephone or Internet. Patients were excluded if they were known to be pregnant, incarcerated, or under policy custody. The age range of 18 to 55 years was chosen because this represents the age group at highest risk for Substance misuse [12]. An initial eligibility screen of potential discharged patients occurred using the ED’s Electronic medical records , and a further in-person assessment in the ED was conducted on patients who met the study criteria after review of the EMR. Patients with continued eligibility were invited to participate, and all participants provided written informed consent. Patients were informed that the study was about pain and use of prescription opioids; they were not aware that misuse was a primary outcome measure. All study procedures were performed after the patient had been discharged from the ED.

Study protocol

Study participants were asked to complete a series of question- naires at 3 points in time: immediately after discharge but before leaving the ED (baseline), 3 days after ED discharge, and 30 days after ED discharge. Day 3 was chosen as the initial follow-up point in order to capture behaviors dealing with prescription opioids that may have been received in the ED, as internal quality improvement data demonstrated 3 days or less to be the most common prescription duration. Thirty days was chosen as a second distal point based on constraints of study feasibility for measuring short-term behaviors related to the index ED visit.

At the baseline, all participants completed questions about age, race and ethnicity, income, education level, insurance status, medical history, history of chronic pain, home medication use (including preexisting prescription opioid use), and the Brief Pain Inventory. The BPI is a 15-item validated instrument composed of 2 multi-item scales measuring pain intensity, pain relief, and interference with activities [13]. All itEMS use an 11-point scale ranging from 0 to 10. The BPI includes the items of pain relief, pain quality, and perceived cause of pain. Pain severity was calculated as the mean score of the 4 pain intensity subscales (ie, worst, least, average, and current pain during the previous 24 hours).

Study coinvestigators also reviewed the EMR to obtain data about the patient’s discharge diagnosis, pain scores from nursing assess- ment, analgesia received in the ED, and discharge prescription information. Patients were then asked to complete follow-up surveys from home at 3 and 30 days after the ED discharge; completion of the 3-day survey was not required to complete the 30-day survey. Surveys were self-administered via an Internet-based software

program (SurveyMonkey Pro, SurveyMonkey, Palo Alto, CA) or were completed by telephone when Internet was unavailable. Patients were asked to complete a repeat assessment of pain using the BPI. They were also asked questions regarding their use of prescribed opioid medications: average dose frequency, maximum amount of pills taken at one time, average amount taken at one time, number of pills used in the last 24 hours, count of remaining pills (day 3 only), need and means for obtaining additional prescription opioids, and use with other pain medications, illicit drugs, or alcohol. Patients were also asked screening questions on misuse adapted from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), Selected Questions on Medication Use [14,15]. This section of the NESARC reads, “Now I’d like to ask you about your experiences with medicines and other kinds of drugs that you may have used on your own–that is, either without a doctor’s prescription (pause); in greater amounts, more often, or longer than prescribed (pause); or for a reason other than a doctor said you should use them. People use these medicines and drugs on their own to feel more alert, to relax or quiet their nerves, to feel better, to enjoy themselves, or to get high, or just to see how they would work.” [15].

On day 30, patients also completed the Drug Abuse Screening Test

(DAST-10). The DAST-10 is a validated tool to detect past 12-month drug abuse, including Illicit substances [16]. The DAST-10 was performed at the end of the study to minimize participants’ bias toward the study’s aims. Participants received $5 and $15 gift cards for completion of the 3- and 30-day surveys, respectively. After completion of the surveys, patients were offered resources about prescription drug abuse and drug abuse treatment.

In order to assess our primary aim, the prevalence of prescription opioid misuse in 18- to 55-year-old patients who were discharged with prescription opioids, we used an opioid misuse definition derived from the NESARC [15]. Using the responses to the 3- and 30-day surveys, patients were classified as misusers if they reported from the time of ED discharge: (1) self-escalation of dose (increasing medication frequency or amount above the level that was prescribed),

(2) use of their prescribed opioid for reasons other than pain, or (3) obtaining prescription opioids without a physician prescription. A patient was also considered to have self-escalated if the amount of pills consumed at one time or in 24 hours exceeded the directions in the original prescription (day 3 only) or the manufacturer’s recommended upper limit based on component of acetaminophen (days 3 and 30).

Once patients were classified as misusers or not, we examined differences in (1) demographics: age, race, ethnicity, income, education level, employment, and insurance status; (2) clinical characteristics: discharge diagnosis, pain score on arrival and at discharge, self-reported history of chronic pain, history of chronic opioid use, analgesia received in the ED, and pain severity as measured by the BPI; and (3) history of drug abuse as measured by the DAST-10.

Data analysis

Descriptive and inferential statistics were performed using STATA

10.0 statistical software (StataCorp LP, College, TX). Outcome measures are presented as means and proportions with 95% confidence intervals (CIs). Odds ratios (ORs) with 95% CIs were used to assess the association between demographic and clinical characteristics, and the presence of prescription opioid misuse.

A priori sample size calculation was not performed because there was inadequate preliminary work to establish effect sizes. An interim power analysis was performed and demonstrated that 83 patients were needed in follow-up in order to detect a 20% incidence of prescription opioid misuse (2-tailed, ? = .1 and ? = 0.8). A more conservative estimate of 20% was chosen based on recent literature

that demonstrated that 32% of patients in a pain clinic on chronic opioids were detected to have opioid misuse [8].

Table 1

Demographic characteristics of misusers and nonmisusers

  1. Results

Misusers (n = 36)

Nonmisusers OR (n = 49)

An overview of study recruitment and enrollment is displayed in

Age (y) Sex, female

37.4 (31.1-37.8) 34.5 (34.0-40.7

21 (58) 31 (63)

) –

0.8 (0.3-1.9)

Fig. 1. We enrolled 103 patients into the study; this represents

marital status, never married

18 (50)

28 (56)

0.8 (0.3-1.8)

approximately 20% of the possible 500 patients who received prescription opioids at discharge during study enrollment shifts Of

Income (annual)

b$10000

8 (22)

19 (38)

0.7 (0.2-2.0)

13 (36)

21 (42)

1.0

$10000-$49999a

the eligible patients screened during recruitment shifts, 91% enrolled

$50000-$99999

2 (6)

6 (12)

0.5 (0.1-3.1)

into the study. Patients were not screened for the study if they did not

N$100000

2 (6)

1 (2)

3.2 (0.3-39.0)

meet the eligibility criteria (eg, non-English speaking, unable to

follow-up) or they were missed (eg, left the ED while another patient

No response

Race

a

11 (31)

18 (50)

3 (6)

28 (56)

1.0

White

was being enrolled). Over a 4-week period during the study, we African American

5 (14)

13 (26)

0.6 (0.2-2.0)

tracked reasons that patients were not screened: 65% were missed Other

13 (36)

8 (14)

because they had left the ED before they could be approached, 10%

met the exclusion criteria, and 25% refused to be screened. Of the 103

Ethnicity, Hispanic Education level

10 (28)

7 (14)

1.8 (0.6-5.3)

enrolled, a total of 76 (74%) patients responded to the day 3 survey, 64

High school or less

At least some collegea

23 (64) 26 (53) 1.8 (0.7-4.4)

11 (30) 22 (45) 1.0

(62%) patients responded to the 30-day survey, 85 (83%) responded to either, and 55 (53%) responded to both. Two-thirds of patients surveyed responded by telephone, with the remainder completing

No response 2 (6) 1 (2) Employment status

Unemployed 8 (22) 11 (22) 1.6 (0.7-2.6)

follow-up by the Internet.

Of the 103 patients recruited, 61% were female. Our recruited

Disabled

Employed or studenta Insurance status

13 (36) 7 (14) 4.0 (1.3-12.2)

14 (39) 30 (60) 1.0

cohort had a higher proportion of women than that of the population

of patients available during enrollment shifts (51%). Other character- istics did not differ between available and recruited patients. The median age was 35 years (range, 18-55 years); 55% were white; 56% had a high school education or less; and median annual income was less than $20 000. Most patients (55%) were discharged with prescriptions for oxycodone, and 39% were given hydrocodone 5/500. At the 3-day follow-up, 25 of 76 (33% [95% CI, 23%-43% ]) respondents self-reported misusing their ED prescription, and at 30-day follow-up, 23 of 64 (36% [25%-47%]) were classified as misusers. Thirty-six of 85 (42% [32%-52%]) patients who responded to either survey reported misuse at one or both follow-up times. Of the 55 patients who responded to both surveys, 12 of 55 (22% [7%-37%]) reported misuse at both follow-

up surveys.

We did not observe a difference in rates of misuse between women and men, 25% vs 36%. Demographic and clinical characteristics of patients with either 3- or 30-day self-reported misuse (misusers) and patients without any self-reported misuse (nonmisusers) are pre-

Insured 28 (78) 36 (73) 1.0

Uninsured 8 (22) 13 (27) 0.8 (0.3-2.2)

Categorical variables are presented as a number (percentage) with associated OR and 95% CIs.

a Refers to the reference category. OR point estimates are bolded when the CI demonstrates significance. Continuous variables are presented as means (95% CI).

sented in Tables 1 and 2, respectively. Based on the point estimate of the OR with 95% CIs, several patient characteristics were associated with misuse: disabled status, history of chronic pain, preexisting opioid use, having received a prescription for oxycodone, and history of substance abuse (DAST-10 scores).

Of all patients reporting misuse, self-escalation of dose was the most common category of misuse, with 92% (33/36 [83%-100%]) of misusers reporting increasing the dose of their prescription opioids without a doctor’s direction. Within the group that self-escalated their prescriptions, 19 of 33 (58% [41-75%]) exceeded the upper limit of the manufacturer’s recommendation based on the component of

Screened for the study the study (n = 113)

Refused (n = 5) Ineligible (n = 5)

Lost to follow-up (n = 18)

Completed either 3 or 30-day follow-up

(n = 85)

Enrolled in the study (n = 103)

Patients available during selected enrollment shifts

(n = 500)

Total patients, aged 18 – 55 who were discharged with a prescription opioid January and February 2013

(n = 2,174)

Completed both follow-ups

(n = 56)

Completed 30-day follow-up only

(n = 64)

Completed 3-day follow-up only (n = 76)

Fig. 1. Study enrollment and retention flow diagram.

Table 2

Clinical characteristics, medication, and substance use among misusers and nonmisusers

Misusers

Nonmisusers

OR

(n = 36)

(n = 49)

History of chronic pain

14 (36%)

9 (18%)

2.8 (1.1-7.6)

Preexisting opioid usea

11 (31%)

5 (10%)

3.9 (1.2-12.4)

Discharge diagnosis

Back

9 (25)

11 (23)

Extremity

9 (25)

13 (27)

Abdominal/pelvic pain

4 (11)

5 (10)

Headache or Dental pain

6 (17)

10 (21)

Infectious/inflammatory

1 (3)

3 (6)

Other

3 (8)

4 (8)

Multiple diagnoses

4 (11)

2 (4)

Arrival pain score

7.7 (6.7-8.6)

7.6 (7.3-8.2)

Discharge pain score 3.8 (2.9-4.6) 4.0 (3.1-5.0)

ED opioids (mg)b 3.9 (2.7-5.0) 4.1 (2.8-5.4)

discharge prescriptions

Hydrocodonec

12 (33%)

28 (57%)

1.0

Oxycodone

23 (61%)

20 (41%)

2.7 (1.1-6.6)

Other opioid

1 (5%)

2 (4%)

Morphine equivalents 52.8 (30.0-74.0) 35.1 (25.3-44.9) (mg)

Prescription length (d)d 2.2 (1.8-2.6) 2.4 (2.1-2.7)

Use with NSAIDs

DAST-10e

4 (11%)

10 (20%)

0.5 (0.1-1.7)

Raw scores

1.9 (1.1-2.8)

0.6 (0.05-1.2)

No riskc

3 (13%)

30 (73%)

1.0

Risk present

20 (77%)

11 (27%)

18.0 (4.5-73.5)

Categorical variables are presented as a number (percentage) with associated OR and 95% CIs.

Abbreviation: NSAIDs, nonsteroidal anti-inflammatory drugs.

a Reported prescription opioids as a home medication on the baseline assessment.

b Opioids administered in the ED, in morphine equivalents.

c Refers to the reference category. OR point estimates are bolded when the CI demonstrates significance. Continuous variables are presented as means (95% CI).

d Length was calculated by taking the maximum dose and minimum frequency if a range was given on the initial prescription.

e Available for 30-day respondents only (n = 64).

acetaminophen. Taking prescription opioids without a doctor’s prescription was reported by 39% (14/36 [23%-55%]) of patients with misuse. Taking pain medications for a reason other than pain was reported by 36% (13/36 [20%-52%]) of misusers. We observed no difference in types of misuse between 3- and 30-day respondents. Among all respondents, there were 6 patients who reported all 3 behaviors of self-escalation, taking prescription opioids without a prescription, and taking prescriptions for a reason other than pain. Detailed characteristics of patients who reported misuse at both 3 and 30 days are presented in Table 3.

There was no appreciable difference in nursing assessment of patients’ pain upon arrival or at discharge from the ED among

Fig. 2. Pain trajectory in misusers vs nonmisusers.

misusers or nonmisusers (Table 2). However, misusers reported a higher level of “pain right now” at baseline assessment (BPI, question 11), which occurred immediately after discharge, 7.5 (6.5-8.5) vs 5.7 (5.1-6.3). In assessing the overall pain trajectory (pain severity over time) among misusers vs nonmisusers, patients with prescription opioid misuse trended toward having an overall increased perception of pain (Fig. 2.). There was no important difference in analgesia received in the ED or at discharge between groups.

  1. Discussion

Prescription opioid misuse is a common concern of emergency care providers, but little has been known about opioid misuse as it relates to opioid prescribing in the ED. To our knowledge, this study is the first to examine the prevalence and characteristics of opioid use behaviors among patients discharged from the ED with opioids. Nearly 4 of every 10 patients in this study reported misusing a prescription opioid at either 3 or 30 days after their ED visit. There was no appreciable difference between misusers and nonmisusers with regard to pain in the ED, treatment of pain in the ED, amount of analgesia received at discharge, or discharge diagnoses in this limited sample. After discharge, however, patients with misuse trended toward having an increased perception of pain severity. In addition, the presence of disability, preexisting prescription opioid use, chronic pain, receiving a prescription for oxycodone (as opposed to another opioid such as hydrocodone), and past 12-month risk of substance abuse were associated with misuse. This suggests that there is an important dynamic between pain, pain management, and misuse that should be explored further. Of interest, only 36% of misusers reporting taking pain medications for a reason other than pain.

We captured a heterogeneous mixture of behaviors among patients in our study who reported misuse. Most patients with

Table 3

Detailed characteristics of patients reporting misuse at both 3- and 30-day follow-up

Age (y)/Sex

Home opioids

DAST-10 Risk

Discharge Prescription

Characteristics of misuse

37/M

Y

Low

Oxycodone

Self-escalated (oxycodone 5/325, 4 tablets/dose); obtained opioids from friend/family; obtained

41/F

Y

Low

Oxycodone

an additional prescription within 48 h of ED discharge

Obtained additional opioids without a prescription

30/M

Y

Mod

Hydrocodone

Used for a reason other than pain; took with illicit drugs

30/M

N

High

Oxycodone

Self-escalated (took 3 oxycodone 5/325, 5x/d); additional prescription within 72 h of ED discharge

39/M

N

None

Oxycodone

Used for a reason other than pain

34/F

Y

Low

Hydrocodone

Obtained additional opioids without a prescription

36/F

Y

Moderate

Hydrocodone

Self-escalated (hydrocodone 5/325, 3-4 tablets 6 x/d); took with illicit drugs

25/F

N

High

Oxycodone

Borrowed opioids from friend/family

55/F

Y

Low

Hydrocodone

Self-escalated (hydrocodone 5/500, 3 tablets 3-5x/d); obtained opioids from friend/family; used for

34/F

N

None

Oxycodone

a reason other than pain

Used for a reason other than pain

24/F

N

Low

Oxycodone

Self-escalated (oxycodone 10 tablets at once); received an additional prescription within 72 h of

49/F

Y

Low

Oxycodone

discharge; obtained medications without a prescription; used for a reason other than pain Self-escalated (oxycodone 5/325, 3 tabs 5 x/d)

Abbreviations: F, female; M, male; N, no; Y, yes.

misuse in this study were considered misusers because of self- escalation, increasing the dose or frequency of prescription opioids without a doctor’s prescription. Although oligoanalgesia may partly be causal of self-escalation, more than half of misusers (22% of the study cohort) exceeded the manufacturer’s recommended safe limits of the drug. In addition, other aberrant behaviors were also captured because a substantial proportion of patients also reported using prescription opioids belonging to someone else or for a reason other than pain. Nearly half of the patients with misuse in our study (n = 17, or 47%) reported misuse in more than 1 category. Of those with more than 1 category of misuse, 2 patients took opioid medications without a prescription and used for a reason besides pain, 4 patients self-escalated and took opioid medications without a prescription, 5 self-escalated and used for a reason besides pain, and 6 patients reported misuse in all 3 categories (7% of all patients in the study cohort). Although we categorized misuse based on behaviors surrounding opioid use, we did not address the issue of diversion and did not we examine the reasons for these different misuse behaviors. Of importance to our study findings, we used a liberal definition of prescription opioid misuse. The term misuse itself is more general and encompassing than the Diagnostic and Statistical Manual of Mental disorders, Fifth Edition criteria for a Drug use disorder (which is concerned with the diagnoses of abuse and dependence) [17]. Specific criteria must be satisfied in order to qualify for the diagnosis of a drug use disorder per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and this would not capture many individuals who are inappropriately using (misusing) their prescription opioids. We believe that individuals with misuse, regardless of the motivation, are still at risk for overdose and may be at risk for the subsequent

development of drug use disorders.

Unfortunately, there is not a uniformly accepted definition of misuse, and this term has come to represent a variety of behaviors leading to assorted nomenclature: nonmedical use, inappropriate medical use, inappropriate therapeutic use, problematic opioid use, recreational use, and not-as-prescribed opioid use among others [5-7]. Most often, misuse is used synonymously with nonmedical use; the National Survey on Drug Use and Health defines nonmedical use as “use of these drugs without a prescription or use that occurs simply for the experience or feeling the drug causes.” [18]. This view of misuse is narrow and misses a significant proportion of patients who misuse prescription opioids.

Subtypes of misuse, based on motivation for misuse (medical or recreational), have been suggested [5,6,19]. Therapeutic misuse, or inappropriate therapeutic use, refers to taking prescription opioids for an indicated reason, but in excess of prescription instructions (more frequent dosing or higher dose), using someone else’s prescription for an indicated reason, or using their opioid prescription for another reason besides the indicated reason (eg, using oxycodone for anxiety or sleep), but not for recreational use. We did not fully delineate therapeutic misuse from nonmedical use or diversion in our study, but future studies should focus on subtypes of misuse. We postulate that a subset of patients in our study were misusing prescription opioids for quasi-legitimate reasons such as uncontrolled pain, as only 36% of patients reported taking prescription opioids for a reason other than pain. Identifying the type of prescription opioid misuse has central relevance to the development of subsequent interventions. Patients with nonmedical use or diversion will likely require different interventions than those with therapeutic misuse (poor pain control, untreated depression or anxiety, etc).

A large proportion of patients with misuse had chronic pain and were already taking opioids. Patients who reported using prescription opioids before their ED visit were 90% more likely to misuse prescription opioids after discharge than patients who did not report prescription opioid use. Dependence, tolerance, opioid-induced hyperalgesia, and abuse, as well as poorly controlled pain may be possible explanations for this finding and are in need of additional

investigation. Opioid-induced hyperalgesia, a heightened sensitivity to pain conferred by opioids, may be associated with poor pain control and misuse [20,21]. Opioid-induced hyperalgesia could have signif- icant implications for the treatment of pain in the ED, pain control after discharge, and subsequent misuse.

Patients who were defined as having some risk for drug abuse as assessed by DAST-10 were associated with misusing their opioids after discharge. Having at least 1 positive question on the DAST-10 assessment was associated with misuse. However, this was only performed in the 30-day respondents and may reflect some bias introduced by not performing this assessment in all misusers. Nonetheless, it emphasizes the potential importance of screening for substance abuse when prescribing opioids. Questions about prior substance abuse have been incorporated into prescription drug misuse screening tools, such as the Opioid Risk Tool [20,22]. Substance abuse screening tools, such as the DAST-10, may be useful in screening those at risk for prescription opioid misuse.

Interestingly, patients who received a prescription for oxycodone had increased odds of misuse compared with those who received hydrocodone (OR, 2.7). Although our data cannot demonstrate a causal relationship, this finding aligns with prior studies that have demonstrated that oxycodone has a higher abuse potential than hydrocodone on a milligram-for-milligram basis [23,24]. Notably, both drugs have been demonstrated to have similar Analgesic efficacy [25,26]. Given that oxycodone and hydrocodone preparations are the most commonly prescribed opioid analgesics, the abuse liability and analgesic profile of each opioid, as well as individual patient factors, should be considered when prescribing.

Limitations

This study is limited by its sample size. It may have been underpowered to detect other significant relationships between demographic or clinical characteristics and prescription opioid misuse. In addition, we only enrolled 18- to 55-year-old English- speaking patients from a single site, which limits the generalizability of these study findings. We enrolled patients in the highest-risk age group to first characterize this problem. If the prevalence of misuse in a high-risk group was low, then it would likely be of poor yield to examine the problem in lower-risk populations. Given that the prevalence of misuse was high, we hope to expand this line of inquiry to other populations (adolescents, older adults, non-English- speaking populations).

We attempted to control for selection and follow-up bias with our recruitment and follow-up procedures. We recruited during randomly assigned study shifts and approached consecutive patients. However, we did miss a large proportion of potentially eligible patients during recruitment shifts. This most often occurred when an eligible patient was discharged and left the ED while another patient was being enrolled. Although it is possible that this could confer selection bias if the reason patients were missed was related to misuse, we do not suspect that this is the case. We did end up with a higher proportion of women (61%) in our recruited sample, in comparison to the overall number ED patients who received Opioid prescriptions during the study period. Although it is possible that this reflects selection bias, this may also have been due to chance given our sample size because the proportion of women in the available population (52%) resides within our 95% CI (51%-71%). Regardless, men historically have had a higher prevalence of substance misuse [27]; therefore, we would expect our prevalence to increase had we recruited a higher proportion of men. In order to increase follow-up, patients provided multiple methods of contact and were allowed to follow up by telephone or Internet. We reminded patients of follow-up by text messaging, telephone, and e-mail. Some patients were inevitably missed or lost to follow-up potentially biasing the results. However,

even if all of the patients lost to follow-up were nonmisusers, the prevalence of misuse would still be 34%.

Furthermore, our study did not delineate other important risk factors for misuse such as depression or alcohol abuse. Likewise, we performed multiple comparisons among a relatively small group, and thus significant, associations need to be confirmed in larger clinical studies. This study was not intended to be an exhaustive evaluation of risk factors for opioid misuse, but rather to provide preliminary groundwork to further study this problem and to gain insight into potential confounders or effect modifiers of misuse.

Importantly, our study is unable to establish the incidence (new cases) of prescription opioid misuse, given that we did not assess existing prescription opioid misuse. We did not perform this baseline evaluation in order to not bias patients to the study’s aims. Moving forward, it will be important to determine the “at-risk” population (those without existing prescription opioid misuse) who go on to develop misuse.

Lastly, the DAST-10 screening occurred on day 30 and not at baseline. This was done not to bias patients toward the aims of the study. It therefore cannot differentiate patients who may have developed drug abuse during the 30-day follow-up period. The DAST-10 is structured to detect past 12-month drug abuse, and we have used it as a proxy for preexisting drug abuse prior to study enrollment.

  1. Conclusion

The results of this small single-center study suggest that misuse of prescription opioids is prevalent among the ED population. Although nonmedical use of prescription opioids has gained widespread attention, patients with therapeutic misuse are likely a more common occurrence. Although the motivation to misuse may be because of elevated perception of pain, these individuals are probably still at risk for opioid overdose, dependence, and abuse. Emergency care pro- viders have an obligation to responsibly prescribe opioids, and these data suggest that additional diligence is due. Although an obligation to treat pain is not obviated, additional research should explore the interaction between pain and misuse, develop measures to identify individuals with current misuse and those at risk for misuse in the ED, explore interventions that improve pain and mitigate misuse, and evaluate outcomes such as overdose and progression to drug use disorder in patients with misuse.

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