Value and Appropriateness of Inpatient Antinuclear Antibody Testing at a Tertiary Hospital
Bibliographic record
Abstract
Objectives Antinuclear antibodies (ANA) are sensitive screening tests for systemic autoimmune rheumatic diseases (SARDs), but positive ANAs lack specificity and can lead to unnecessary patient anxiety and healthcare use. The appropriateness of ANA testing in hospitalized patients at our institution remains unclear. We aimed to characterize inpatient ANA testing, including the proportion ordered in the setting of possible signs or symptoms of a SARD, the proportion with a final diagnosis of a SARD, and the proportion for which testing was potentially unnecessary. Methods We reviewed 50 randomly sampled patients who had an ANA test ordered during a hospitalization at our institution (June-October 2023), collecting patient demographics, reasons for ANA testing, results, and hospitalization details from electronic medical records. We reviewed post-discharge records to ascertain new documented SARD diagnoses. We defined ANA testing as potentially unnecessary if the individual (1) already had an established ANA-associated condition at the time of testing, (2) lacked signs or symptoms of a SARD or unexplained liver disease, (3) had an ANA result from our laboratory within the past year. Results Of the 50 charts reviewed, 24 (48%) were female, with a mean age of 61.7 (standard deviation, SD 19.6) years at time of ANA testing. Two patients had known conditions associated with ANA. ANA was positive in 37 (74%) patients at a titer of ≥1:80 (72% at ≥1:160), with the most common pattern reported at highest titer being homogenous (46%). A third of the tests were ordered by general internists, and 2% were ordered by rheumatologists. Fifteen (30%) had a prior ANA result at our institution (8 within the past year), with a median interval of 46.8 days (Interquartile range 6-3897) from the prior ANA test. Additionally, 5 (10%) had the ANA test repeated within the same inpatient stay. Most ANAs were ordered as part of an autoimmune work-up for pulmonary disease (22%) and neurological/psychiatric presentations (20%). Seven (14%) were ordered without apparent signs or symptoms attributable to a SARD or autoimmune hepatitis. Of the 25/37 (68%) individuals with a +ANA who had post-discharge follow-up at our institution after the ANA result was reported (median follow-up 221 days post-discharge [IQR 107-270]), zero (95% Confidence Interval, 0-13%) had documentation of a new SARD diagnosis or another autoimmune condition. Overall, 17 (34%) ANA tests (95% CI 22-48%) were potentially unnecessary. Conclusion Our institution could benefit from systems to guide appropriate ANA testing, in particular repeat ANA testing.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.019 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".