CORR Insights®: What Are the MCIDs for PROMIS, NDI, and ODI Instruments Among Patients With Spinal Conditions? (2018)

Where Are We Now? One way to assess value in health care is to divide the benefit to the patient by the number of dollars spent [7]. The increasing emphasis on value-based health care shifted providers’ focus from radiographic to patient-centered outcomes. Consequently, having validated and relevant tools that assess quality of life, functional outcomes, and pain is of critical importance. Patient-reported outcomes measures (PROMs) quantify a variety of endpoints that patients care about: pain, function, activity level, and in some cases, satisfaction [14] and are increasingly being used to evaluate healthcare expenditures, assess cost-effectiveness [5], determine compensation [3], risk-stratify patients [10], and predict outcomes [9]. As such, PROMs are important to various stakeholders, including patients, physicians, payers, and healthcare institutions. Physicians who treat patients with spinal disorders use a number of PROMs that cover disease-specific disability, pain, and health-related quality of life; some of these include the Oswestry Disability Index (ODI), Neck Disability Index (NDI), Visual Analog Scale for pain, Short Forms, and EuroQol-5D. While ODI and NDI historically have been the most-commonly used PROMs, Patient-Reported Outcomes Measurement Information System (PROMIS) is a relatively new outcome measure that is increasingly being implemented because of its length and ease of use, which decrease the burden on patients. PROMIS uses computer adaptive testing (CAT)-based instruments to measure health outcomes from the patient’s perspective. Prior to CAT-based instruments, a patient might have skipped questions (s)he considered irrelevant [11]; this can occur when using traditional PROMs like the ODI or the NDI. By contrast, in a CAT-based test like PROMIS, the test automatically eliminates questions determined to be irrelevant by that patient’s answers to earlier questions, which reduces the burden on the patient. This test may also be less prone to floor and ceiling effects [11]. The validity and utility of PROMIS in orthopaedic patients is well-documented [2, 6], particularly in those undergoing spine surgery [1, 12, 13]. PROMIS data also have been shown to be more efficient, flexible and precise than those yielded by other PROMs. Several of these studies have reported that PROMIS CAT outperforms ODI and is highly correlated with ODI, Short-Form questionnaires, and other older outcome tools in spine patients, while also taking less time to administer, with fewer questions to answer [12, 13]. Still, the clinical relevance of PROMIS data in patients with spinal disorders has not been determined, particularly for patients’ PROMIS scores on perception of their own health, and what constitutes a meaningful change to the patient. The current study by Hung and colleagues [8] helps to fill this gap by determining the minimum clinically important difference (MCID) for the PROMIS Physical Function and Pain Interference domains, which are most relevant to patients with spine disorders. The study concludes with an interesting proposition—since the MCID varies considerably depending on the method used for calculation, and there is no consensus regarding which method is preferred, it may be more suitable to think of MCID as a range of values, rather than a single fixed number, and that the appropriate value be selected depends on what one wishes to do with the information. Where Do We Need To Go? Measuring and tracking patients’ perceptions of their health with the use of PROMs is critical in enhancing the value of spine care and promoting evidence-based decision making. A better understanding of what the data represented by various PROM scores mean is indispensable. There is no consensus regarding the best method to calculate the MCID. As MCID values vary based on the methods used for their calculation, there will be a range of MCID values for each measure. While this may be beneficial in terms of offering various interpretative options and the ability to select an appropriate value based on the purpose, there is currently little or no evidence to guide this selection, thus leaving this decision to individual discretion. This lack of clear direction reduces the generalizability and comparability of reports that utilize the MCID as a benchmark for assessing outcomes, which ultimately has implications in terms both of clinical decision-making and research. Since the current study provides a range of values of MCID for PROMIS, it is vital to establish which method is most appropriate in which setting, and to have clear guidelines to assist with this selection. Chung and colleagues [4] suggest that MCID values for certain PROMs vary for different types of treatment modalities (surgical vs. nonsurgical, type of surgery), possibly due to variations in patient expectation. The patients included in the current study were all patients aged 18 or older seen by a spine specialist at a university orthopaedic clinic. While it is important to keep the results generalizable to a large patient population, the validity and applicability of these results in a particular treatment or diagnosis populations needs to be assessed, and treatment-specific or diagnosis-specific MCID values may need to be established. How Do We Get There? The use of PROMs to assess value in health care is becoming increasingly important. As more precise and more patient-friendly outcome measures such as PROMIS are introduced, it becomes vital to establish methods to evaluate the true value and utility of these measures and to interpret their clinical implication and relevance. Larger studies that allow for stratification by diagnosis and treatment, and studies that focus on specific patient populations will be beneficial to assess the validity of the currently established MCID values in other populations, determine if diagnosis-specific or treatment-specific MCID values are required, and guide the selection of the most appropriate MCID calculation method for various settings. If larger studies are not financially feasible, researchers should consider patient-reported outcome studies since they tend to be less expensive as clinical trials and usually just take longer to complete. Further research on the use of PROMIS to track outcomes in spine surgery will contribute to the development of evidence, which can be used to guide patient-centered care based on patients’ perspectives, and thus, enhance the value of spine care.