PROMIS Pain Interference Is Superior to the Likert Pain Scale for Pain Assessment in Spine Patients

David N. Bernstein, MBA, MA; Matthew St. John, MD, MS; Paul T. Rubery, MD; Addisu Mesfin, MD

Disclosures

Spine. 2019;44(14):E852-E856. 

In This Article

Abstract and Introduction

Abstract

Study Design: Cross-sectional cohort analysis.

Objective: (1) To assess the correlation between Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) and pain interference (PI) in patients seeking spine care; (2) to assess the correlation between PROMIS PF and the Likert Pain Scale (LPS) in patients seeking spine care; (3) to determine which pain scale best correlates to physical function overall and by number of clinic visits.

Summary of Background Data: An accurate understanding of a patient's pain level is beneficial in setting clinical and pain management expectations. There is limited work analyzing which instrument best captures pain and its impact on function in patients seeking spine care.

Methods: Spine center patients from February 2015 to November 2017 were asked to complete PROMIS PF and PI domains, as well as to report their pain level on a 0 (no pain) to 10 (worst pain) LPS at each visit. Pearson correlation coefficients were calculated between PROMIS PF and PROMIS PI; PROMIS PI and LPS; and PROMIS PF and LPS. Fisher rz transformation method was utilized for confidence intervals (CIs) and to determine significant correlation differences. Analyses were performed for all data, as well as by office visit. Significance was set at P < 0.01.

Results: A total of 21,774 first visit, 11,130 second visit, 6575 third visit, 4202 fourth visit, and 2819 fifth visit patients' data were recorded. PROMIS PF demonstrated a moderate correlation with the LPS over all visits (r = 0.46–0.49, P < 0.01). PROMIS PF demonstrated a strong correlation with PROMIS PI over all visits (r = 0.73–0.77, P < 0.01). Overall, PROMIS PI demonstrated significantly better correlation to self-reported physical function than the LPS (P < 0.01).

Conclusion.While PROMIS PI and the LPS both demonstrated significant correlation with self-reported physical function, PROMIS PI had a significantly stronger correlation.

Level of Evidence: 2

Introduction

There is an increasing focus in healthcare finance on value—defined as health outcome achieved per dollar spent[1]—as opposed to absolute quantity of service. With this paradigm shift, accurately measuring the outcomes most important to patients becomes critical. Two important outcomes that impact value in spine care are function and pain. Traditionally, many clinics have utilized the 0 to 10 Likert pain scale (LPS) that denotes 0 as representing "no pain" and 10 representing the "worst pain possible" or a similar visual analogue scale (VAS).[2] The main difference between the two scales is that the VAS allows patients to report their pain level along a spectrum on a continuous scale; in contrast, the LPS is discontinuous and segmented (e.g., 0, 1, 2, etc.).[3] However, there are concerns about ceiling and floor effects in such legacy instruments.[4] In addition, while potentially useful in some clinic settings, the LPS may not be a truly valid outcome measurement; thus, a robust, validated patient-reported outcome (PRO) instrument that is universally utilized would add significant value to patient care.[5] This would ensure a complete patient evaluation, while also reducing redundancies and clinic inefficiencies.

There continue to be discussions around the role of PROs in value-based healthcare reform.[6] At the core, PRO instruments allow patients a louder voice in their own care by providing a structured way to incorporate their input into shared decision-making scenarios. One possible unifying set of PRO tools is the Patient-Reported Outcomes Measurement Information System (PROMIS), a validated, general PRO instrument with support from the National Institutes of Health (NIH) that utilizes item response theory (IRT) as part of a computerized adaptive test (CAT).[7] Prior research involving PROMIS in spine care has demonstrated its concurrent validity to legacy spine instruments, such as the Oswestry Disability Index (ODI),[8] Neck Disability Index (NDI),[9] as well as its value in helping to assess postoperative success in lumbar discectomy.[10] Research has begun to examine the relationship of PROMIS PF to the VAS,[8,11] which has been shown to be concurrently valid to the LPS.[12] However, there has been no study assessing whether PROMIS pain interference (PI) better captures the impact of pain on self-reported physical function than legacy PRO pain instruments, such as the LPS.

To date, PROMIS has been implemented into a number of medical settings and a great deal of surgical research has taken place.[13] As the call for greater integration of PROMIS into routine clinical care increases,[14] the need to evaluate the potential benefit of PROMIS compared with traditional PRO instruments grows. This study had three main objectives: (1) to assess the correlation between PROMIS physical function (PF) and PI in patients seeking spine care; (2) to assess the correlation between PROMIS PF and the LPS in patients seeking spine care; (3) to determine which pain scale best correlates to physical function overall and by number of clinic visits.

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