Hatakka Juho, Pernaa Katri, Kostensalo Joel, Mäkelä Keijo, Laaksonen Inari
Department of Orthopedics and Traumatology, Turku University Hospital, and University of Turku, Turku, Finland.
Natural Resources Institute Finland, Natural Resources, Joensuu, Finland.
Int J Spine Surg. 2025 Mar 6;19(1):110-116. doi: 10.14444/8699.
The Oswestry Disability Index (ODI) is a well-validated and widely used patient-reported outcome instrument to evaluate lumbar spinal stenosis (LSS) patients' treatment outcomes. The objective of the present study was to determine long the average interval between 2 preoperative measurements can be before a clinically significant difference of 10 points or more might appear.
This was a retrospective observational study utilizing prospectively collected data from a single university hospital database, which was compatible with the national registry. One hundred and four surgically treated LSS patients were included in this observational study using systematic sampling. The preoperative ODI score was obtained at 2 timepoints. The 2-month mark as a potential turning point was of special interest, as the registry in question excludes preoperative data as outdated if the data are older than 2 months. Possible time dependence of the change in ODI scores was explored using a linear mixed-effects model with ODI as the dependent variable and interval length, sex, age, body mass index (BMI), and the presence of a concomitant disease as fixed effects.
The mean ODI score was 41.7 points (SD = 16.0) at the first and 41.1 points (SD = 15.5) at the second measurement. Mean time between the ODI scores was 74 days (range 8-361). On average, ODI changed by 9.17 points (SD = 7.16) between the 2 measurements, increasing for 48 patients, remaining unchanged for 9 patients, and decreasing for 47 patients. The arithmetic mean of the changes was -0.60 points and the median was 0.00 points. The estimated change in the population mean was -0.0005 points/day (95% CI [-0.022, 0.022], = 0.97), meaning that we have strong evidence that the change in the mean is not clinically significant for up to 15 months (95% CI between ±10 points). Furthermore, no evidence was found that age, sex, BMI, or concomitant diseases were associated with the change of ODI score over time. Furthermore, the probability to observe a clinically significant change in a patient did not depend on the number of days between the 2 measurements (OR 1.003, 95% CI [0.997, 1.010], = 0.30). Variance in ODI change did not grow over time.
The probability of observing a clinically significant differences does not depend on the length of the observation interval, and ODI scores can be considered equally reliable for a significantly longer time than 2 months, even up to 1 year.
Preoperative ODI scores do not lose reliability up to 1 year in patients undergoing operatively treatment for LSS.
奥斯威斯利残疾指数（ODI）是一种经过充分验证且广泛应用的患者报告结局工具，用于评估腰椎管狭窄症（LSS）患者的治疗效果。本研究的目的是确定两次术前测量之间的平均间隔时间可以延长到多久，才可能出现10分或更高的具有临床意义的差异。
这是一项回顾性观察性研究，利用从单一大学医院数据库前瞻性收集的数据，该数据库与国家登记处兼容。采用系统抽样方法，104例接受手术治疗的LSS患者被纳入本观察性研究。在两个时间点获取术前ODI评分。将2个月标记作为一个潜在的转折点特别受关注，因为所讨论的登记处如果术前数据超过2个月则将其作为过时数据排除。使用以ODI为因变量、间隔长度、性别、年龄、体重指数（BMI）和合并疾病的存在作为固定效应的线性混合效应模型，探讨ODI评分变化可能的时间依赖性。
第一次测量时ODI平均评分为41.7分（标准差=16.0），第二次测量时为41.1分（标准差=15.5）。两次ODI评分之间的平均时间为74天（范围8 - 361天）。两次测量之间，ODI平均变化9.17分（标准差=7.16），48例患者升高，9例患者不变，47例患者降低。变化的算术平均值为-0.60分，中位数为0.00分。总体均值的估计变化为-0.0005分/天（95%置信区间[-0.022, 0.022]，P = 0.97），这意味着我们有充分证据表明，在长达15个月（95%置信区间在±10分之间）内，均值变化无临床意义。此外，未发现年龄、性别、BMI或合并疾病与ODI评分随时间的变化相关。此外，观察到患者出现具有临床意义变化的概率不取决于两次测量之间的天数（比值比1.003，95%置信区间[0.997, 1.010]，P = 0.30）。ODI变化的方差不随时间增加。
观察到具有临床意义差异的概率不取决于观察间隔的长度，并且ODI评分在超过2个月甚至长达一年的显著更长时间内都可被认为具有同等可靠性。
对于接受LSS手术治疗的患者，术前ODI评分在长达1年的时间内不会失去可靠性。
