Thomas Keller

Dr. Thomas Keller

orcid

Research Focus & Metrics

Academic Career Length

34Years (1993-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 March 2010 in American Journal of Clinical Pathology
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Journal Article
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CBChristine Bergeron
Christine Bergeron
Jaume OrdiJaume Ordi
Jaume Ordi
DSDietmar Schmidt
Dietmar Schmidt
MTMarcus J. Trunk
Marcus J. Trunk
TKThomas Keller
Thomas Keller
RRRuediger Ridder
Ruediger Ridder
The histopathologic interpretation of cervical intraepithelial neoplasia (CIN) is subject to a high level of interobserver variability and a substantial number of false-positive and false-negative results. We assessed the impact of the conjunctive interpretation of p16INK4a-immunostained slides on the accuracy of community-based pathologists in diagnosing high-grade cervical intraepithelial neoplasia (CIN; CIN 2 and CIN 3) in biopsy specimens. Twelve pathologists rendered independent diagnoses on a set of 500 H&E-stained cervical punch and conization specimens. Results were compared with a dichotomized “gold standard” established by consensus of 3 gynecopathology experts. When p16INK4a-immunostained slides were added and conjunctively interpreted with the H&E-stained slides, a significant increase in diagnostic accuracy for the detection of high-grade CIN was observed (P = .0004). Sensitivity for high-grade CIN was increased by 13%, cutting the rate of false-negative results in half. Agreement of community-based pathologists in diagnosing high-grade CIN was significantly improved (mean κ values advanced from 0.566 to 0.749; P < .0001). Reproducibility of p16INK4a stain interpretation was excellent (κ = 0.899). Our results show that conjunctive interpretation of p16INK4a-stained slides could significantly improve the routine interpretation of cervical histopathology.

4 October 2013 in JNCI: Journal of the National Cancer Institute
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Journal Article
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HIHans Ikenberg
Hans Ikenberg
CBChristine Bergeron
Christine Bergeron
DSDietmar Schmidt
Dietmar Schmidt
HGHenrik Griesser
Henrik Griesser
FAFrancisco Alameda
Francisco Alameda
FGfor the PALMS Study Group
for the PALMS Study Group
Pap cytology is known to be more specific but less sensitive than testing for human papillomavirus (HPV) for the detection of high-grade cervical intraepithelial neoplasia (CIN2+). We assessed whether p16/Ki-67 dual-stained cytology, a biomarker combination indicative of transforming HPV infections, can provide high sensitivity for CIN2+ in screening while maintaining high specificity. Results were compared with Pap cytology and HPV testing. A total of 27349 women 18 years or older attending routine cervical cancer screening were prospectively enrolled in five European countries. Pap cytology, p16/Ki-67 immunostaining, and HPV testing were performed on all women. Positive test results triggered colposcopy referral, except for women younger than 30 years with only positive HPV test results. Presence of CIN2+ on adjudicated histology was used as the reference standard. Two-sided bias-corrected McNemar P values were determined. The p16/Ki-67 dual-stained cytology positivity rates were comparable with the prevalence of abnormal Pap cytology results and less than 50% of the positivity rates observed for HPV testing. In women of all ages, dual-stained cytology was more sensitive than Pap cytology (86.7% vs 68.5%; P < .001) for detecting CIN2+, with comparable specificity (95.2% vs 95.4%; P = .15). The relative performance of the tests was similar in both groups of women: younger than age 30 and 30 years or older. HPV testing in women 30 years or older was more sensitive than dual-stained cytology (93.3% vs 84.7%; P = .03) but less specific (93.0% vs 96.2%; P < .001). The p16/Ki-67 dual-stained cytology combines superior sensitivity and noninferior specificity over Pap cytology for detecting CIN2+. It suggests a potential role of dual-stained cytology in screening, especially in younger women where HPV testing has its limitations.

25 March 2015 in Surgical Endoscopy
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Journal Article
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FKF. Köckerling
F. Köckerling
RBR. Bittner
R. Bittner
DJD. A. Jacob
D. A. Jacob
LSL. Seidelmann
L. Seidelmann
TKThomas Keller
Thomas Keller
AKA. Kuthe
A. Kuthe
Introduction More than 20 years since the introduction of TAPP and TEP into clinical routine, there is a lack of clarity due to conflicting comparative data. Therefore, more results from registries are needed. Patients and methods A total of 17,587 patients were enrolled prospectively between September 1, 2009, and April 15, 2013, in the Herniamed registry. Of these patients, 10,887 (61.9 %) had a TAPP and 6700 (38.1 %) a TEP repair. The dependent variables were intra- and postoperative complication rates, number of reoperations as well as absolute and relative frequencies. The results of unadjusted analyses were verified via multivariable analyses. Results Multivariable analysis verified the results of unadjusted analysis, indicating that the surgical technique did not have any significant impact, also while taking account of other factors, on occurrence of intraoperative [p = 0.1648; OR = 1.214 (0.923; 1.596)] and general postoperative complications [p = 0.0738; OR = 1.315 (0.974; 1.775)]. Postoperative surgical complications [OR = 2.323 (1.882; 2.866); p < 0.0001] were noted more often after TAPP. Furthermore, the hernia defect size [p < 0.0001; I vs III: OR = 0.439 (0.313; 0.615), II vs III: OR = 0.712 (0.582; 0.872)] or scrotal [p < 0.0001; OR = 2.170 (1.501; 3.137)] hernia and age [p = 0.0002; 10-year OR = 1.135 (1.062; 1.213)] had a significant impact on the occurrence of postoperative complications. Complications were observed more commonly for larger hernia defects and a scrotal hernia. However, the difference in the postoperative complication rate between TEP and TAPP did not result in any difference in the reoperation rate (TEP 0.82 % vs TAPP 0.90 %; p = 0.6165). Conclusion The intraoperative and general postoperative complication rates as well as the reoperation rate for complications show no significant difference between TEP and TAPP. The higher postoperative complication rate for TAPP, which could be managed conservatively, is partly explained by larger defect sizes, more scrotal hernias and older age.

1 March 2018 in Clinical Chemistry
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WMW. Greg Miller
W. Greg Miller
HSHeinz Schimmel
Heinz Schimmel
RRRobert Rej
Robert Rej
NGNeil Greenberg
Neil Greenberg
FCFerruccio Ceriotti
Ferruccio Ceriotti
HVHubert W. Vesper
Hubert W. Vesper
Commutability is a property of a reference material (RM) that relates to the closeness of agreement between results for an RM and results for clinical samples (CSs) when measured by ≥2 measurement procedures (MPs). Commutability of RMs used in a calibration traceability scheme is an essential property for them to be fit for purpose. Similarly, commutability of trueness controls or external quality assessment samples is essential when those materials are used to assess trueness of results for CSs. This report is part 1 of a 3-part series describing how to assess commutability of RMs. Part 1 defines commutability and addresses critical components of the experimental design for commutability assessment, including selection of individual CSs, use of pooled CSs, qualification of MPs for inclusion, establishing criteria for the determination that an RM is commutable, generalization of commutability conclusions to future measurements made with the MPs included in the assessment, and information regarding commutability to be included in the certificate for an RM. Parts 2 and 3 in the series present 2 different statistical approaches to commutability assessment that use fixed criteria related to the medical decisions that will be made using the laboratory test results.

1 March 2018 in Clinical Chemistry
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GNGöran Nilsson
Göran Nilsson
JBJeffrey R. Budd
Jeffrey R. Budd
NGNeil Greenberg
Neil Greenberg
VDVincent Delatour
Vincent Delatour
RRRobert Rej
Robert Rej
WMW. Greg Miller
W. Greg Miller
A process is described to assess the commutability of a reference material (RM) intended for use as a calibrator, trueness control, or external quality assessment sample based on the difference in bias between an RM and clinical samples (CSs) measured using 2 different measurement procedures (MPs). This difference in bias is compared with a criterion based on a medically relevant difference between an RM and CS results to make a conclusion regarding commutability. When more than 2 MPs are included, the commutability is assessed pairwise for all combinations of 2 MPs. This approach allows the same criterion to be used for all combinations of MPs included in the assessment. The assessment is based on an error model that allows estimation of various random and systematic sources of error, including those from sample-specific effects of interfering substances. An advantage of this approach is that the difference in bias between an RM and the average bias of CSs at the concentration (i.e., amount of substance present or quantity value) of the RM is determined and its uncertainty estimated. An RM is considered fit for purpose for those MPs for which commutability is demonstrated.

28 November 2006 in BMC Surgery
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Journal Article
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Ulrich SackUlrich Sack
Ulrich Sack
BBBirgit Biereder
Birgit Biereder
TETino Elouahidi
Tino Elouahidi
KBKatrin Bauer
Katrin Bauer
TKThomas Keller
Thomas Keller
RTRalf-Bodo Tröbs
Ralf-Bodo Tröbs
Acute appendicitis (AA) is a common surgical problem that is associated with an acute-phase reaction. Previous studies have shown that cytokines and acute-phase proteins are activated and may serve as indicators for the severity of appendicitis. The aim of this study was to compare diagnostic value of different serum inflammatory markers in detection of phlegmonous or perforated appendicitis in children. Data were collected prospectively on 211 consecutive children. Laparotomy was performed for suspected AA for 189 patients. Patients were subdivided into groups: nonsurgical abdominal pain, early appendicitis, phlegmonous or gangrenous appendicitis, perforated appendicitis. White blood cell count (WBC), serum C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), acid α1-glycoprotein (α1GP), endotoxin, and erythrocyte sedimentation reaction (ESR) were estimated ad the time of admission. The diagnostic performance was analyzed using receiver operating characteristic (ROC) curves. WBC count, CRP and IL-6 correlated significantly with the severity of appendiceal inflammation. Identification of children with severe appendicitis was supported by IL-6 or CRP but not WBC. Between IL-6 and CRP, there were no significant differences in diagnostic use. Laboratory results should be considered to be integrated within the clinical assessment. If used critically, CRP and IL-6 equally provide surgeons with complementary information in discerning the necessity for urgent operation.