Socioeconomic disadvantage is correlated with worse PROMIS outcomes following lumbar fusion.

BACKGROUND CONTEXT

Socioeconomic status (SES) has been associated with differential healthcare outcomes and may be proxied using the area-deprivation index (ADI). Few studies to date have investigated the role of ADI on patient-reported outcomes and clinically meaningful improvement following lumbar spine fusion surgery.

PURPOSE

The purpose of this study is to investigate the role of SES on lumbar fusion outcomes using Patient-Reported Outcomes Measurement Information System (PROMIS) surveys.

STUDY DESIGN/SETTING: Retrospective review of a single institution cohort.

PATIENT SAMPLE

About 205 patients who underwent elective one-to-three level posterior lumbar spine fusion.

OUTCOME MEASURES

Change in PROMIS scores and achievement of minimum clinically important difference (MCID).

METHODS

Patients 18 years or older undergoing elective one-to-three level lumbar spine fusion secondary to spinal degeneration from January 2015 to September 2021 with minimum one year follow-up were reviewed. ADI was calculated using patient-supplied addresses and patients were grouped into quartiles. Higher ADI values represent worse deprivation. Minimum clinically important difference (MCID) thresholds were calculated using distribution-based methods. Analysis of variance testing was used to assess differences within and between the quartile cohorts. Multivariable regression was used to identify features associated with the achievement of MCID.

RESULTS

About 205 patients met inclusion and exclusion criteria. The average age of our cohort was 66±12 years. The average time to final follow-up was 23±8 months (range 12-36 months). No differences were observed between preoperative baseline scores amongst the four quartiles. All ADI cohorts showed significant improvement for pain interference (PI) at final follow-up (p<.05), with patients who had the lowest socioeconomic status having the lowest absolute improvement from preoperative baseline physical function (PF) and PI (p=.01). Only those patients who were in the lowest socioeconomic quartile failed to significantly improve for PF at final follow-up (p=.19). There was a significant negative correlation between socioeconomic level and the absolute proportion of patients reaching MCID for PI (p=.04) and PF (p=.03). However, while ADI was a significant predictor of achieving MCID for PI (p=.02), it was nonsignificant for achieving MCID for PF.

CONCLUSIONS

Our study investigated the influence of ADI on postoperative PROMIS scores and identified a negative correlation between ADI quartile and the proportion of patients reaching MCID. Patients in the worse ADI quartile had lower chances of reaching clinically meaningful improvement in PI. Policies focused on alleviating geographical deprivation may augment clinical outcomes following lumbar surgery.