Postoperative outcomes after degenerative lumbar spine surgery in rheumatoid arthritis patients -a propensity score-matched analysis

A practical guide to estimating treatment effects in patients with rheumatic diseases using real-world data

OBJECTIVE

Randomized controlled trials are considered the gold standard in study methodology. However, due to their study design and inclusion criteria, these studies may not capture the heterogeneity of real-world patient populations. In contrast, the lack of randomization and the presence of both measured and unmeasured confounding factors could bias the estimated treatment effect when using observational data. While causal inference methods allow for the estimation of treatment effects, their mathematical complexity may hinder their application in clinical research.

METHODS

We present a practical, nontechnical guide using a common statistical package (Stata) and a motivational simulated dataset that mirrors real-world observational data from patients with rheumatic diseases. We demonstrate regression analysis, regression adjustment, inverse-probability weighting, propensity score (PS) matching and two robust estimation methods.

RESULTS

Although the methods applied to control for confounding factors produced similar results, the commonly used one-to-one PS matching method could yield biased results if not thoroughly assessed.

CONCLUSION

The guide we propose aims to facilitate the use of readily available methods in a common statistical package. It may contribute to robust and transparent epidemiological and statistical methods, thereby enhancing effectiveness research using observational data in rheumatology.

Psoriatic arthritis increases the risk of venous thromboembolism following degenerative lumbar spine surgery: An analysis of U.S. Nationwide Inpatient Sample 2005-2018

Background

This retrospective study aimed to determine the risk of venous thromboembolism (VTE) in patients with PsA after surgery for lumbar degenerative disease (LDD).

Methods

The study data of adults aged ≥20 years admitted to U.S. hospitals with diagnoses of LDD and undergoing spinal decompression or fusion between 2005 and 2018 were extracted from the National Inpatient Sample (NIS) database. Patients were further divided into two groups based on a diagnosis of PsA or not via codes ICD-9: 696.0 and ICD-10: L40.50. Patients with missing information were excluded. Propensity score matching (PSM) was employed to enhance comparability between groups. Logistic regression was used to determine associations between PsA and various outcomes, including complications, unfavorable discharge, and prolonged length of stay (LOS).

Results

Data on 471,283 patients with LDD was extracted from the NIS database.from 2005 to 2018. Before propensity score matching, patients with PsA had higher proportions of overall morbidity (8.8 % vs. 6.9 %), VTE (1.4 % vs. 0.7 %), and unfavorable discharge (20.8 % vs. 16.9 %). After matching, patients with PsA still had higher VTE incidence and unfavorable discharge proportions. After adjustments, multivariable regression analysis indicated that patients with PsA had a higher risk of unfavorable discharge (aOR: 1.26, 95 % CI: 1.03-1.55) and VTE (aOR: 1.99, 95 % CI: 1.05-3.75).

Conclusions

Among patients undergoing surgery for LDD, pre-existing PsA may be associated with increased risks of unfavorable discharge and VTE occurrence. The findings may benefit preoperative risk stratifications before LDD surgeries.

Rheumatoid arthritis patients are at increased risk for adverse events following lumbar discectomy

BACKGROUND CONTEXT

Lumbar discectomy is a common procedure for which patients with rheumatoid arthritis (RA) may be considered. RA is an autoinflammatory disease that may predispose patients to postoperative adverse outcomes.

PURPOSE

To assess the relative odds of adverse events after lumbar discectomy for those with versus without RA in a large, national, administrative dataset.

STUDY DESIGN/SETTING

Retrospective cohort study using the 2010 to 2020 MSpine PearlDiver dataset.

PATIENT SAMPLE

After exclusion of patients under 18 years old, those with any trauma, neoplasm, or infection diagnosis within the month before lumbar discectomy, and any patients who had any alternative lumbar spinal surgery performed on the same day as lumbar discectomy, we identified 36,479 lumbar discectomy patients. 2,937 (8.1%) of these patients had a prior diagnosis of RA. After matching 4:1 by patient age, sex, and Elixhauser Comorbidity Index (ECI, a longitudinal measure of patient comorbidity burden generated via ICD-9 and 10 diagnosis codes), 8,485 lumbar discectomy patients without RA and 2,149 with RA were included.

OUTCOME MEASURES

Incidence of severe and minor adverse events in the 90-days following lumbar discectomy, predictive factors for adverse events within 90-days of lumbar discectomy, risk of adverse events within 90-days of lumbar discectomy stratified by patient medication regimen, 5-year survival to reoperation following lumbar discectomy.

METHODS

Patients undergoing lumbar discectomy were identified from the PearlDiver MSpine dataset. The subset of those with versus without RA were identified and matched 1:4 based on patient age, sex, and ECI scores. The incidence of 90-day adverse events in the two groups was determined and compared by univariate and multivariate analyses. Subgroup analysis was performed based on RA medications being taken.

RESULTS

Matched lumbar discectomy patients with RA (n=2,149) and without RA (n=8,485) were identified. Controlling for patient age, sex, and ECI, those with RA were at significantly higher odds of any (odds ratio [OR] 3.30), severe (OR 2.78), and minor (OR 3.30) adverse events (p<.0001 for all). Stratifying by medications being taken (and relative to those without RA), there was increasing odds of all adverse events (AAE) based on potency of medications (no biologic or disease modifying antirheumatic drugs [DMARDs] OR 2.33, DMARDs only OR 3.86, biologic±DMARDs OR 5.69 (p<.0001 for all). Despite this, no statistically significant difference in 5-year survival from subsequent lumbar surgery was found between those with versus without RA (p=.1000).

CONCLUSIONS

Lumbar discectomy patients with RA were found to be at significantly higher risk for 90-day adverse events following lumbar discectomy, and this was incrementally greater for those on increasingly suppressive medications. Lumbar discectomy patients with RA bear specific consideration and perioperative monitoring when considered for lumbar discectomy.