PT Interventions & Opioid Use After TKR

• Prognosis aims to predict future patient outcomes
• EBP (Evidence Based Practice) uses article analysis

Article Overview: PT Interventions and Opioid Use After TKR

• Aoyagi, Neogi, Peloquin et al. conducted research on the association between PT interventions and long-term opioid use after total knee replacement (TKR)
• The study appeared in JAMA Network Open. 2021;40(0); e2131271

Authors' Argument: Opioid Use in TKR Patients

• TKRs serve as a primary treatment for knee osteoarthritis (OA)
• Post-operative pain persists in 20-30% of patients after undergoing TKR
• Initial opioid prescriptions can lead to long-term opioid use
• Opioid use affects 32.5%-35.0% of opioid-experienced individuals and 2.2%-2.4% of opioid-naive individuals long-term after TKR

Relevance of Physical Therapy (PT)

• PT correlates with increased function.
• PT reduces the risk of opioid addiction and long-term opioid use
• PT can reduce pain and opioid use, but optimal methods (dosage, timing, type) are unclear

Aspects of PT Care Investigated

• Pre- and post-TKR PT
• Dosage and timing of PT
• Active vs. passive PT interventions
  • Active PT includes exercise and gait training
  • Passive PT includes modalities, TENS, and cold therapy
• Studies look at PT interventions before and after TKR to see if post-rehab care would help with pain

Purpose Statement

• Evaluating the associations of PT interventions before and after TKR with long-term opioid use
• PT dosage and timing affects outcomes

Identifying Data Source

• OptumLabs Data Warehouse provides data, containing medical & pharmacy claims
• Includes lab results
• Enrollment records of approximately 67,000 individuals

Importance of Insurance Coverage

• Subjects had commercial insurance or Medicare Advantage, which affects generalizability
• Full database members had full insurance coverage
• Lacking insurance as a confounding factor
  • Not participating in PT due to access or other factors

Confounding Factors

• A confounding factor distorts the true relationship between an exposure and an outcome
• It relates to both the exposure and the outcome

Key Inclusion Criteria

• Broad insurance coverage
• Age ≥40 years
• TKR between 2001-2016
• Continuous insurance for 24 months pre- and post-TKR follow-up

Exclusion Criteria

• Previous history of comorbidities, rheumatoid arthritis (RA), or cancer
• Pts Could already be on different drugs
• Knee surgery, rheumatoid arthritis, or cancer within 24 months of the study

Categorizing Individuals

• Opioid-experienced individuals had ≥2 opioid prescriptions pre-TKR
• Opioid-naive individuals had no opioid prescriptions in 12 months pre-TKR
• Separate group had only 1 prescription, for sensitivity study

Exposure

• PT intervention (pre- and post-TKR, different doses, timing)

Cohort Study

• Group classified by exposure, observes outcome development over time
• Prospective or Retrospective
• Measures incidence, relative risk (RR)
• Best for rare exposures
• Involves exposure, wait for outcome.

Risk Ratio

• Compares risk of an event in an exposed group vs. non-exposed
• Example: 10/100 smokers get lung cancer versus 2/100 non-smokers
• RR = 10%/2% = 5
• Smokers are 5 times more likely to develop lung cancer

Outcome

• Long-term opioid use

Case-Control Study

• Compares cases (with outcome) to controls (without)
• Looks back at exposures retrospectively
• Measures odds ratio (OR)
• Best for rare outcomes
• Involves starting with outcome then looking back at exposure like asking cancer patients about past smoking.

Odds Ratio

• Compares odds of an event between groups, not actual risk
• Example: 10/15 cancer patients are smokers vs 2/10 healthy controls
• Odds of smoking are two in cancer patients
• Odds of smoking are 0.25 in healthy controls
• OR = 2/0.25 = 8
• Cancer patients had 8 times higher odds of being smokers

Research Design

• Retrospective cohort study
• Examines relationships between past exposures and outcomes

Exposure Variables

• Pre-TKR PT: Any PT within 90 days before surgery
• Post-TKR PT: Any PT within 90 days after surgery
• Post-TKR PT dose: 1-5, 6-12, or ≥13 sessions
• Post-TKR PT timing: <30, 31-60, or 61-90 days after TKR
• Post-TKR PT type: Active (exercise, gait training) vs. passive (TENS, cold therapy)

Outcome Variable

• Long-term opioid use (≥90 days' worth of filled prescriptions post-TKR)

Measurement

• Identified via pharmacy claims and prescriptions in 12 months post-TKR

Confounders

• Other variables that affect outcome
• Must be controlled when causal relationships are looked at
• Can bias results if correlated with both exposure and outcome
• Randomization is difficult in this design (demographic/longitudinal)

Importance in this Type of Study

• Confirm effects are not due to age, gender etc
• Observational studies can't randomly assign interventions
• Confounder control crucial

Confounders Authors Refer To

• Age, sex, race/ethnicity, obesity, insurance type
• Geographical location, physical and mental health comorbidity

Impactful Confounders

• Insurance, most impactful confounding factors region, comorbidities
• Pre-TKR pain severity, mental health conditions, and healthcare access,is most impactful

Statistical Analyses

• Regression analysis to estimate associations between PT and long-term opioid use

Regression Analysis Details

• If dependent variable is continuous → multiple linear regression
• If dependent variable is categorical/nominal → logistic regression

Regression Analysis Description

• Examines the relationship between independent variables (predictors) and a dependent variable (outcome).
• Models relationships to predict or understand associations

Logistic Regression

• Type of regression with a binary dependent variable with 2 outcomes yes/no, and if it will successfull/failure.
• Models the chance of an event based on independent variables
• Result expressed as odds ratios or probabilities

Multiple Linear Regression

• Type of regression with a continuous dependent variable
• Predicts it using 2+ independent variables
• Assumes a linear relationship

Figure 2 and Table 1

• Figure 2 is a participant flow diagram (prisma) and flowchart showing study inclusion criteria and participant selection.
• Involes Inclusion criteria process and two study groups

Two groups

• Opioid-naive individuals had no prior opioid use
• Opioid-experienced individuals had used opioids

Similarities

• Both are primarily female
• Most participants were from the Midwest, South, and West, limited northeast representation
• Insurance spread is about the same

Differences

• Opioid experienced individuals have more obese members than opioid-naive
• Opioid Experienced have more NSAID use
• Opioid experienced report more pain
• Opioid experienced group presents more psychological issues

Table 2

• Table related to logistic regression, table for prognostic study for future disease course based on data study of condition

Pre-TKR PT Impact

• Opioid-naive: Lower odds (aOR 0.75, 95% CI 0.60-0.95), decreased 25%
• Opioid-experienced: Lower odds (aOR 0.75, 95% CI 0.70-0.80)

Post-TKR PT Effects

• Opioid-experienced: Lower odds (aOR 0.75, 95% CI 0.70-0.79)
• Opioid-naive: No significant effect as confidence interval for odds ratio includes 1.0

Table 3 Results

• Post-TKR PT intervention characteristics affect long-term opioid use

Post TKR PT Doses

• Not statistically significant for opioid-naive individuals as confidence interval includes 1
• Significant effect opioid experienced individuals, more sessions associated with less opioid use, including 29% decrease for > 13 session and 18% decrease for for 6-12 sessions

Post TKR PT Timing

• The sooner you get therapy the better the outcomes
• Delayed PT initiation increased odds of opioid use
• Statistically significant for opioid naive individuals

Post TKR PT Type

• Post TKR PT type shows no difference between active vs. passive and not a significant difference for either

Take-Home Messages

• More sessions linked to lower opioid use
• Delayed PT increased opioid use odds

Sensitivity Analysis Justification

• Analysis remains constant and Findings remained consistent

Sensitivity Analysis Use

• Determines how input values affect a system's outcome
• Assesses outcome sensitivity to changes in input variables
• This informs decisions by understanding variability and risks

Limitations

• Confounding bias occurred
• Patients in PT less likely to use opioids already Solution: RCT, or propensity score matching

Lack of Adjustment Between States

• Regulations/coverage differences affected PT/opioid use Solution: Adjust for state-level access or stratified analysis

Exposure Issues

• Post-TKR PT extended beyond 90 days, while pre-TKR PT was fixed, creates unevenness Solution: Standardize timeframe for groups

Ownership Issues

• Varying models/incentives impacted PT quality/quantity Solution: Include type of practice into the analysis

Missing Data Issues

• Functional status data lacked no baseline
• Worse status results skewed opioids/PT relationship Solution: Collect/adjust status in assessments

Solution Instead of BMI

• Data lacked BMI leading to residual confounding Solution: Use of alternative metrics

Conclusion

• Pre- and post-TKR PT linked to less opioid use
• Some PT factors (sessions/timing) further cut opioid use
• Opioid use matters when recommending PT for TKR patients

Evidence Strength

• Study show correlation but not causation due factors
• Design limits claims vs randomized trials
• Evidence is moderately strong to be strong RCT with factor adjustment
• Study did not measure minor adverse events, and the long-term effects beyond 3 months were not assessed and effects of standardization were not considered