Integrating Anti-Phosphatidylserine/Prothrombin Antibodies Testing into Antiphospholipid Syndrome Diagnostics: A Multidomain, Expert Perception-Based Health Technology Assessment

<b>Background</b>: Antiphospholipid syndrome (APS) is diagnosed by characteristic clinical manifestations supported by positivity for lupus anticoagulant, anticardiolipin, and anti-β2-glycoprotein I antibodies. However, a proportion of patients, especially those with systemic lupus erythematosus, remain seronegative despite high clinical suspicion. Anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have emerged as potential biomarkers in this setting. We conducted an <i>expert perception-based</i> Health Technology Assessment (HTA) to evaluate the clinical, ethical, and organizational impact of implementing aPS/PT testing. <b>Methods</b>: A structured HTA was performed across five domains: safety, perceived efficacy, equity, ethics, and organizational implications. A survey was distributed to 110 APS specialists; 50 experts contributed responses (45.5% response rate; 66% clinicians, 18% laboratory personnel, 8% nurses, 8% administrative/other). For each domain, Z-scores were calculated to compare current diagnostic practice (AS IS) with a scenario integrating aPS/PT testing (TO BE). Correlation analyses explored relationships across domains. <b>Results</b>: Across all five domains, the TO BE scenario scored substantially higher than standard practice. The largest improvements were observed in perceived diagnostic efficacy (ΔZ = +2.65) and safety (ΔZ = +2.03), followed by equity (ΔZ = +2.25), ethical/social impact (ΔZ = +1.96), and organizational feasibility (ΔZ = +1.61). Perceived diagnostic effectiveness showed a strong positive correlation with both equity (r = 0.70, <i>p</i> < 0.001) and ethics (r = 0.67, <i>p</i> < 0.001). Participants consistently rated the assay as safe, clinically useful, equitable, and organizationally easy to introduce in routine laboratory workflows. <b>Conclusions</b>: Experts perceived the addition of aPS/PT testing as a meaningful enhancement to APS diagnostics, particularly for SLE patients who are seronegative on conventional assays. Its favorable profile across all HTA domains supports further evaluation in prospective cohorts and consideration for integration into future diagnostic algorithms.