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Assay Performance and Quantification Limits in Perioperative Serum Cytokine Measurement After Total Hip Arthroplasty: A Secondary Laboratory Analysis

Year: 2026
Type: article
Abstract: Background: Commercial cytokine assays may not span the concentrations encountered in perioperative serum. We examined the extent to which reconstructed enzyme-linked immunosorbent assay data from a total hip arthroplasty cohort could support temporal biological interpretation when most IL-6 and IL-10 results were below the validated quantification range. Methods: This post hoc secondary laboratory analysis used serum collected preoperatively and at 6, 24, and 48 h later from 44 of 52 participants in a single-centre three-arm trial. Five cytokines were measured by sandwich ELISA. Optical-density (OD) values were reconstructed from scanned reports and triangulated across three transcriptions. OD trajectories were summarised with within-patient rank tests as exploratory assay-signal observations. Five omnibus tests were Holm-adjusted across analytes. Detectability was analysed as a paired binary outcome using Cochran’s Q and exact McNemar comparisons with Holm correction. Clinical characteristics, acute-phase markers, and missing-data structure were evaluated in the assayed subcohort. Results: The assayed subcohort included all 18 no-block participants and 26 of 34 block recipients; the 8 non-assayed participants were late-enrolled block recipients. IL-6 OD varied over time (Friedman raw p = 2.6 × 10−11; Holm-adjusted p = 1.3 × 10−10), but 154/176 readings (87.5%) were below the LLOQ. IL-6 detectability was 0/44, 9/44, 7/44, and 6/44 at the four timepoints (Cochran Q = 12.27, p = 0.0065); only the preoperative-to-6 h McNemar comparison remained significant after correction (adjusted p = 0.023). TNF-alpha, IL-1alpha, and IL-10 OD also varied in exploratory analyses, whereas IL-1beta was inconclusive. CRP rose from a median 0.20 mg/dL preoperatively to 7.70 mg/dL at 24 h and 14.55 mg/dL at 48 h in the same 44 participants. Conclusions: The data document an assay-range and data-recovery problem more securely than they establish cytokine kinetics. The reconstructed OD changed systematically after surgery, especially for IL-6, but measurements below the validated range cannot establish concentration ordering, cross-cytokine dominance, or counter-regulation. Because re-assaying was not possible, all biological interpretations are presented as tentative and non-transferable. The reproducible findings are the extent of censoring, the limits of the available assay records, and the need to match the assay range to expected perioperative concentrations before clinical sampling.
DOI: 10.3390/jcm15207829
Language: English
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7221532600
FWCI:
Cites: 29
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Related to: 10