Curtis Helen J, Fisher Louis, Evans David, Bacon Sebastian, Mehrkar Amir, Goldacre Ben, MacKenna Brian
Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, England, OX2 6GG, UK.
Wellcome Open Res. 2024 Jul 2;8:541. doi: 10.12688/wellcomeopenres.19858.2. eCollection 2023.
Numeric results of pathology tests are sometimes returned as a range rather than a precise value, e.g. "<10". In health data research, test result values above or below clinical threshold values are often used to categorise patients into groups; however comparators (<, > etc) are typically stored separately to the numeric values and often ignored, but may influence interpretation.
With the approval of NHS England we used routine clinical data from 24 million patients in OpenSAFELY to identify pathology tests with comparators commonly attached to result values. For each test we report: the proportion returned with comparators present, split by comparator type and geographic region; the specific numeric result values returned with comparators, and the associated reference limits.
We identified 11 common test codes where at least one in four results had comparators. Three codes related to glomerular filtration rate (GFR) tests/calculations, with 31-45% of results returned with "≥" comparators. At least 90% of tests with numeric values 60 and 90 represented ranges (≥60 and ≥90 respectively) rather than exact values. The other tests - four blood tests (Nucleated red blood cell count, Plasma C reactive protein, Tissue transglutaminase immunoglobulin A, and Rheumatoid factor), two urine tests (albumin/microalbumin) and two faecal tests (calprotectin and quantitative faecal immunochemical test) - were returned with "≤" comparators (29-86%).
Comparators appear commonly in certain pathology tests in electronic health records. For most common affected tests, we expect there to be minimal implications for researchers for most use-cases. However, care should be taken around whether results falling exactly on clinical threshold values should be considered "normal" or "abnormal". Results from GFR tests/calculations cannot reliably distinguish between mild kidney disease (stage G2, 60-<90) versus healthy kidney function (90+). More broadly, health data researchers using numeric test result values should consider the impact of comparators.
病理检查的数值结果有时以范围形式给出，而非精确值，例如“<10”。在健康数据研究中，高于或低于临床阈值的检查结果值常被用于将患者分类；然而，比较运算符（<、>等）通常与数值分开存储，且常被忽略，但它们可能会影响解读。
经英国国民保健制度（NHS）英格兰地区批准，我们使用了OpenSAFELY中2400万患者的常规临床数据，以识别结果值通常附有比较运算符的病理检查。对于每项检查，我们报告：附有比较运算符的结果所占比例，按比较运算符类型和地理区域划分；附有比较运算符返回的具体数值结果，以及相关的参考限值。
我们识别出11个常见检查代码，其中至少四分之一的结果附有比较运算符。三个代码与肾小球滤过率（GFR）检查/计算相关，31% - 45%的结果附有“≥”比较运算符返回。数值为60和90的检查中，至少90%表示范围（分别为≥60和≥90）而非精确值。其他检查——四项血液检查（有核红细胞计数、血浆C反应蛋白、组织转谷氨酰胺酶免疫球蛋白A和类风湿因子）、两项尿液检查（白蛋白/微量白蛋白）和两项粪便检查（钙卫蛋白和定量粪便免疫化学检查）——附有“≤”比较运算符返回（29% - 86%）。
比较运算符在电子健康记录的某些病理检查中似乎很常见。对于大多数常见的受影响检查，我们预计在大多数用例中对研究人员的影响最小。然而，对于恰好落在临床阈值的结果应被视为“正常”还是“异常”，应谨慎对待。GFR检查/计算的结果无法可靠地区分轻度肾病（G2期，60 - <90）与健康肾功能（90+）。更广泛地说，使用数值检查结果值的健康数据研究人员应考虑比较运算符的影响。
