National Trends and Factors Associated With Inpatient Mortality in Adult Patients With Opioid Overdose

Brittany N. Burton, MHS, MAS; Timothy C. Lin, MAS; Engy T. Said, MD; Rodney A. Gabriel, MD, MAS

Disclosures

Anesth Analg. 2019;128(1):152-160. 

In This Article

Results

There were 584,373 patients with a diagnosis of either POD or IOD from 2010 to 2014. After excluding patients with missing data (2.29%), our final sample included 570,987 patients, of which 13.8% and 86.2% had a diagnosis of IOD and POD, respectively. Table 2 outlines the distribution of patient and hospital characteristics. Patients with IOD were younger than patients with POD (31 vs 52 years old; P < .001). The proportion of patients with POD versus IOD was higher in Caucasian (81.5% vs 74.1%) and Native American (0.9% vs 0.4%) patients (P < .001). Female (56.6% vs 29.1%) patients were more likely to have POD, while male (70.9% vs 43.4%) patients tended to have IOD (P < .001). Patients with IOD were more likely to live in zip codes with the lowest quartile of median household income (P < .001). Medicare (41.1%) was more common among those with POD; however, Medicaid (33.9%) was more common among those with IOD (P < .001). Uninsured patients had higher rates of IOD versus POD (P < .001). Rural (13.9%) and urban (41.3%) nonteaching hospitals had higher unadjusted rates of POD inpatient diagnoses (P < .001).

National Trends

In our unadjusted logistic regression model, IOD admissions increased by 24% per year (OR, 1.24; 95% CI, 1.22–1.25; P < .001); however, POD admissions decreased by 19% per year (OR, 0.81; 95% CI, 0.80–0.82; P < .001; Figure 1A). In our sociodemographic-adjusted logistic regression model, IOD admissions increased by 31% per year (OR, 1.31; 95% CI, 1.29–1.31; P < .001); however, POD admissions decreased by 24% per year (OR, 0.76; 95% CI, 0.75–0.77; P < .001). The overall mortality rate was 2.6%. Furthermore, we estimated a 4.7% and 2.3% mortality rate among IOD and POD admissions, respectively (Table 3). In the unadjusted logistic regression analysis, the odds of inpatient mortality increased by 8% per year among IOD admissions (OR, 1.08; 95% CI, 1.02–1.14; P < .007) and by 6% per year among POD admissions (OR, 1.06; 95% CI, 1.03–1.09; P < .001; Figure 1B). In the sociodemographic-adjusted logistic regression analysis, the odds of inpatient mortality increased by 9% per year among IOD admissions (OR, 1.09; 95% CI, 1.03–1.15; P = .003) and by 6% per year among POD admissions (OR, 1.06; 95% CI, 1.03–1.09; P < .001). Figure 2 shows the prevalence of IOD and POD admissions among all inpatient admissions in the NIS database during 2010–2014. IOD is more prevalent in the Northeast (69 per 100,000 hospital admissions) and Midwest (60 per 100,000 hospital admissions) geographical regions, whereas POD is leading along the Western region (311 per 100,000 hospital admissions).

Figure 1.

Opioid overdose in the United States: 2010–2014. Solid line represents IOD, and dashed line represents POD. A, Among all opioid overdose admissions, the unadjusted odds of IOD admissions increased by 23% per year (OR, 1.23; 95% CI, 1.22–1.25; P < .001); however, the unadjusted odds of POD admissions decreased by 19% per year (OR, 0.81; 95% CI, 0.80–0.82; P < .001). B, The odds of inpatient mortality increased significantly among IOD admissions (OR, 1.08; 95% CI; 1.02–1.14; P = .007) and POD admissions (OR, 1.06; 95% CI, 1.03–1.09; P < .001). CI indicates confidence interval; IOD, illicit opioid overdose; OR, odds ratio; POD, prescription opioid overdose.

Figure 2.

Rate of opioid overdose per 100,000 among all inpatient admissions by US geographical region: 2010–2014. Geographical regions are defined as Northeast, Midwest, South, and West. A, Prevalence IOD among all inpatient admissions. B, Prevalence of POD among all inpatient admissions. IOD indicates illicit opioid overdose; POD prescription opioid overdose.

Comorbidities, Interventions, and Outcomes Characteristics

Table 3 lists the distribution of comorbidities, inpatient interventions, and outcomes of patients admitted with opioid overdose. Active smoking (37%), hypertension (31.4%), depression disorder (25.9%), and benzodiazepine poisoning (25.8%) were the most common comorbidities among the overall study population. The median number (interquartile range) of diagnoses per inpatient was 12 (9–16). Compared to POD, patients with IOD tended to have a diagnosis of cocaine abuse and poisoning, central nervous system stimulant poisoning, amphetamine poisoning, alcohol abuse, opioid abuse, cannabis abuse, active smoker, hallucinogen poisoning, suicidal ideation, pneumonitis, metabolic acidosis, cardiac dysrhythmias, rhabdomyolysis, leukocytosis, or septicemia (all P < .05). The most common inpatient interventions included mechanical ventilation (21.1%) followed by noninvasive mechanical ventilation (4.5%) and cardiac evaluation (3.4% [eg, electrocardiogram, diagnostic ultrasound, and cardiac catheterization]) (P < .001). The median hospital length of stay was longer for POD versus IOD (3 vs 2 days; P < .001). Hospital charge was higher for POD (P < .001). Unadjusted mortality was significantly more common among patients with IOD (P < .001).

Factors Associated With Mortality

Figure 3 lists the results of inpatient mortality of the mixed-effects multivariable logistic regression analysis. We included an unweighted number of 116,407 patients in the regression analysis. Those with IOD compared to POD had higher odds of mortality (OR, 1.73; 95% CI, 1.56–1.94; P < .001). The odds of inpatient mortality were decreased in African American versus Caucasian patients (OR, 0.67; 95% CI, 0.57–0.79; P < .001), in patients undergoing alcohol rehabilitation therapy (OR, 0.19; 95% CI, 0.09–0.41; P < .001), and in patients with chronic pain (OR, 0.55; 95% CI, 0.49–0.61; P < .001). The odds of inpatient mortality were increased in patients 80+ years of age versus 18–49 years old (OR, 2.36; 95% CI, 1.91–2.91; P < .001) and in patients with solid tumor malignancy (OR, 2.44; 95% CI, 2.13–2.80; P < .001). For inpatient mortality, model discrimination demonstrated an area under the receiver operating characteristic curve (95% CI) of 0.9141 (0.9093–0.9189).

Figure 3.

Mixed-effect multivariable logistic regression analysis of factors associated with inpatient mortality. CI indicates confidence interval; CPR, cardiopulmonary resuscitation; IOD, illicit opioid overdose; OR, odds ratio; POD, prescription opioid overdose; RBC, red blood cell.

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