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Comparative Analysis of Length of Stay, Hospitalization Costs, and Opioid use among Spine Surgery Patients with Postoperative Pain Management including IV versus Oral Acetaminophen
Friday, 8:00 AM - 10:00 AM
Indigo 202A

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Comparative Analysis of Length of Stay, Hospitalization Costs, Opioid Use, and Discharge Status among Spine Surgery Patients with Postoperative Pain Management including IV versus Oral Acetaminophen


► Recovery from spine surgery is oriented toward restoring functional health outcomes while reducing hospital length of stay (LOS) and medical expenditures. Optimal pain management is a key to reaching these objectives.

► Prior research suggests that IV acetaminophen (IV APAP) for acute pain improves patient outcomes and reduces hospital resource use.

► We compared the outcomes of spine surgery patients who received standard pain management including either IV APAP or oral APAP.


Data source, timeframe, and study cohort

► We performed a retrospective analysis of the Premier database (between January 2012 and September 2015) comparing inpatient spine surgery patients who received pain management with IV APAP to those who received oral APAP starting on the day of surgery and continuing up to the third postoperative day.

► Spine surgeries were identified using International Classification of Diseases version 9 procedure codes. Among those subjects, the receipt of IV APAP and oral APAP was identified using service records, with no exclusions based on additional pain management.


► We compared the groups on:

-LOS from hospital admission to discharge day
-Total hospitalization cost
-Average morphine equivalent dose (MED)
-Discharge to skilled nursing facilities (SNF)

Statistical analysis

► For adjusted analyses, we performed multivariable logistic regression for the binary outcomes and separate instrumental variable regressions comparing the LOS, hospitalization costs, and average MED. The quarterly rate of IV APAP use for all hospitalizations by hospital was used as an instrumental variable in two-stage least squares regressions with the following covariates:

-Patient: Age, Gender, Race
-Admission type
-3M APR-DRG severity of illness (SOI) and
-Risk of mortality (ROM)
-Hospital bed count
-Indicators for whether the hospital was an academic center and whether it was urban or rural

Patient demographics

► We identified 112,586 spine surgery patients with 51,835 (46%) who had received IV APAP (Table 1).

► Study subjects averaged 57 and 59 years of age and were predominantly non-Hispanic Caucasians (>70% both cohorts) and female (52% and 55%, respectively in the IV and oral APAP cohorts).

► The majority of subjects were in the minor or moderate category for both the APR-DRG SOI and ROM.

Unadjusted analysis

► The mean unadjusted LOS for IV APAP patients was 3.2 days (SD 3.8) compared to 4.9 days (SD 6.5) with oral APAP, a statistically significant difference of -1.6 days (p<0.0001) (Table 2).

► Average unadjusted hospitalization costs were $24,800 (SD $20,713) for IV APAP patients and $29,366 (SD $28,817) for oral APAP patients, also statistically significantly lower by $4,566 (p<0.0001).

► The average MED for IV APAP patients was 43.1 mg (SD 55.2) and 50.8 mg (SD 66.6) for oral APAP patients, a statistically significant difference of -7.7 mg (p<0.0001).

► IV APAP patients were 48% less likely to be discharged to a SNF (Table 2).

► IV APAP patients were 28% less likely to develop bowel obstruction, 27% less likely to develop nausea/vomiting, and 45% less likely to develop respiratory depression (Table 3).

Adjusted analysis

► In our adjusted models, IV APAP was associated with 0.7 days shorter hospitalization (95% CI: -0.8 to -0.6, p<0.0001), $1,175 lower hospitalization costs (95% CI: -$1,611 to -$739, p<0.0001), and 13 mg lower average MED (95% CI: -14 mg to -12 mg, p=<0.0001) (Table 4).


► The differences observed between IV APAP and oral APAP patients could be explained by unmeasured confounders. Investigators attempted to account for this through the use of instrumental variable regression, adjusting models for potentially confounding variables, but unmeasured factors might still play a role in the associations reported.

► The medication use data in the Premier database reflects the amount and dose charged rather than what was administered. However, systematic differences in billing of other pain medications between patients who did or did not receive IV APAP is not suspected. 

► The population of patients seen in Premier hospitals is not randomly sampled. Therefore these results may not be generalizable outside of Premier hospitals (20% of US hospitals).


► Compared to oral APAP in the adjusted models, managing post-spine surgery pain with IV APAP is associated with shorter LOS, decreased total hospitalization costs, lower doses of opioids, reduced risk of complications, and reduced risk of discharge to a skilled nursing facility. 

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