PROPOSING FORMAL CLINICAL DIAGNOSTIC CRITERIA FOR POST-EPIDURAL PDPH BASED ON LONG-TERM FOLLOWUP FROM THE CANADIAN PDPH TRIAL
Abstract Number: T 15
Abstract Type: Original Research
Introduction: Advances in management of post-epidural PDPH cannot occur without consistent use of meaningful diagnostic criteria for this outcome in clinical trials. We report on the performance of 2 sets of diagnostic criteria compared within the Canadian PDPH trial (Formal Study Criteria/primary outcome) vs International Headache Society Criteria)(Ref 1). These were judged using an Umpire Reference Test(standardized long-term followup for CSF leakage symptoms)as the clinical gold standard.
Methods: After REB approval and patient consent, this multicenter RCT randomized laboring women to receive a large (≥18g)vs small (19g) epidural needle for labor analgesia. The primary outcome was PDPH based on Study Diagnostic Criteria as adjudicated by a blinded external group of experts within the first 14 days of epidural placement. Experts also adjudicated cases for evidence of PDPH based on IHS criteria. First pass agreement between adjudicators was assessed using kappa followed by a consensus diagnosis if required. A second external independent headache specialist/neurologist, examined all 184 previously adjudicated cases, blinded to needle and previous diagnoses, over the full course of study/clinical followup( maximum 1year) for a diagnosis of symptoms consistent with CSF leakage as an Umpire Reference Test.
Results: 1080 women were recruited. Study criteria demonstrated improved first pass interrater reliability between adjudicators for PDPH diagnosis (Kappa 0.93,95%CI 0.85,1.0) vs IHS Criteria(kappa 0.70, 95% CI 0.49, 0.92). PDPH was diagnosed in 25/184 cases based on Study Criteria vs 16/184 using IHS criteria. Thirty-one/184 of these same cases were diagnosed with CSF leakage based on longterm followup (Umpire Reference Test). Study Criteria demonstrated improved diagnostic performance compared with IHS Criteria against the Umpire Reference Test: Sensitivity 71% (vs 36%),Specificity 98%(vs 97%), NPV 94% (vs 88%), PPV 88% (69%), LR+36 (12,142) (vs LR 10.9 (3.9, 34).
Discussion: Study Criteria demonstrated improved diagnosis of CSF leakage symptoms post-epidural compared with IHS criteria based on long-term patient followup. A significant number of women with post-Epidural PDPH are currently undetected in clinical practice and research. We believe that our clinical diagnostic criteria should be adopted for standardized use in patient care and research.
References: Cephalagia, 24,supp 1, 2004.
Table 1. PDPH Trial DIAGNOSTIC CRITERIA FOR PDPH POST-EPIDURAL
Formal Study Criteria
1.Postural headache or neckache that occurs or worsens within 15minutes of sitting/standing and improves within15minutes of lying down. Symptoms may include visual or auditory symptoms, neck stiffness, tinnitus, diplopia, photophobia, nausea/vomiting
2. Patients may or may not have a recognized dural puncture (after epidural needle placement in the spine)
3. Headache and/or neckache persists at least 24 hours and occurs <14 days of epidural needle placement