Page 57 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

Predictive value of interim PET in DLBCL
authors and for six studies we used the KM curves without numbers at risk. For two studies we could not extract the HRs, as there was insufficient data and no Kaplan-Meier curve [36,48].
In Fig. 2 the Forest plot with the 18 univariate HRs is shown. The pooled effect estimate was 3.13 (95% CI 2.52–3.89). The Cochran’s Q test for heterogeneity was not statistically significant (P = 0.087) and between study heterogeneity was low (I2 = 35.14%). The 95% prediction interval was 1.68–5.83, with one outlier [37].
The methodological quality was assessed based on the QUADAS-2 and QUIPS checklists. Subgroup analyses were performed on study design characteristics that were potential sources of bias.
Meta-regression showed that the outcomes did not differ between retrospective and prospective studies, studies with blinded review and studies that did not report whether they blinded the PET/CT assessment, or studies that used PFS or EFS as outcome measure. A statistically significant higher HR was found for studies with a combination of integrated PET/CT- and PET standalone systems compared to studies with integrated PET/CT systems only (HR 4.39 vs 2.85, P =0.0332) and a trend towards a higher HR in studies with 80–99% DLBCL compared to studies with 100% DLBCL (P =0.0577). Prespecified subgroups for different types of treatments and FDG-PET scoring systems showed no statistically significant differences (Supplemental Table 3). For the subgroups “availability of baseline PET or CT” and “central or local review procedure”, insufficient information was reported to perform these analyses. Risk of publication bias as assessed with a Funnel plot was low (Supplemental Fig. 1).
Nineteen studies had data available for the calculation of PPV, NPV, sensitivity, and specificity of interim PET for prediction of two-year-PFS or -EFS. For one study we could not extract or calculate the diagnostic measures [48]. PPV and NPV ranged from 20 to 74% and 64 to 95%, respectively. Sensitivity and specificity ranged from 33 to 87% and 49 to 94%, respectively (Table 3, Supplemental Fig. 2).
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