Week 3 Discussion
Serum samples were drawn before surgery. No chemotherapy, radiotherapy, or targeted
therapy was usedprior to blood collection. For each patient, 8 mL of peripheral blood was
obtained by venous puncture, followed by centrifugation at 3000 g for 10 min at 4C. Cellfree
serum was then stored at 80C until RNA extraction. Control samples were
obtained from 105 patients with benign liver disease (BLD) (75 patients with alcoholic
liver disease and 30 patients with nonalcoholic fatty liver disease, all without hepatitis B
infection) and 105 healthy volunteers (both age- and sex-matched).
The relative expression of serum UCA1 was detected and analyzed in each sample using
reverse- transcription PCR
Umemneku Chikere, C. M., Wilson, K., Graziadio, S., Vale, L., & Allen, A. J. (2018).
Diagnostic test evaluation methodology: A systematic review of methods employed to
evaluate diagnostic tests in the absence of gold standard – An update. PLoS ONE, 14(10).
https://doi.org/10.1371/journal.pone.0223832
in the patient-control studies, the patients have to undergo the reference standard before the
index test. In fact, people known to be affected by the target disease (“patients”) and people
who are not affected (“controls”; i.e., healthy people or people with other diseases than the one
we want to discriminate) are selected according to the results of the reference standard.
Patient-control studies may be affected by spectrum bias which produces an overestimation of
the index test accuracy.
https://aasldpubs.onlinelibrary.wiley.com/doi/10.1002/hep.26948
This question is exemplified by a patient-control study on des-gamma carboxy-prothrombin
(DCP) for the diagnosis of hepatocellular carcinoma (HCC).15 Fifty-five patients with
histologically proven HCC in liver cirrhosis (patients) and 53 patients with histologically
proven liver cirrhosis (controls) were included. The mean serum concentration of DCP and the
proportion of patients with a raised DCP value above the 125-mAU/mL cutoff were higher in
patients with HCC (target disease). Another question is: are patients with a more advanced
stage of the target disease more likely to have “abnormal” index test values than patients with
a less severe target disease? To answer this question, a study has to include patients with
different stages of the target disease. The study design is, again, the patient-control study
(selection of groups of patients with a known stage of the disease).
This document is made available for students merely for even better practice,
preparation and brainstorming purposes.
Serum samples were drawn before surgery. No chemotherapy, radiotherapy, or targeted
therapy was usedprior to blood collection. For each patient, 8 mL of peripheral blood was
obtained by venous puncture, followed by centrifugation at 3000 g for 10 min at 4C. Cellfree
serum was then stored at 80C until RNA extraction. Control samples were
obtained from 105 patients with benign liver disease (BLD) (75 patients with alcoholic
liver disease and 30 patients with nonalcoholic fatty liver disease, all without hepatitis B
infection) and 105 healthy volunteers (both age- and sex-matched).
The relative expression of serum UCA1 was detected and analyzed in each sample using
reverse- transcription PCR
Umemneku Chikere, C. M., Wilson, K., Graziadio, S., Vale, L., & Allen, A. J. (2018).
Diagnostic test evaluation methodology: A systematic review of methods employed to
evaluate diagnostic tests in the absence of gold standard – An update. PLoS ONE, 14(10).
https://doi.org/10.1371/journal.pone.0223832
in the patient-control studies, the patients have to undergo the reference standard before the
index test. In fact, people known to be affected by the target disease (“patients”) and people
who are not affected (“controls”; i.e., healthy people or people with other diseases than the one
we want to discriminate) are selected according to the results of the reference standard.
Patient-control studies may be affected by spectrum bias which produces an overestimation of
the index test accuracy.
https://aasldpubs.onlinelibrary.wiley.com/doi/10.1002/hep.26948
This question is exemplified by a patient-control study on des-gamma carboxy-prothrombin
(DCP) for the diagnosis of hepatocellular carcinoma (HCC).15 Fifty-five patients with
histologically proven HCC in liver cirrhosis (patients) and 53 patients with histologically
proven liver cirrhosis (controls) were included. The mean serum concentration of DCP and the
proportion of patients with a raised DCP value above the 125-mAU/mL cutoff were higher in
patients with HCC (target disease). Another question is: are patients with a more advanced
stage of the target disease more likely to have “abnormal” index test values than patients with
a less severe target disease? To answer this question, a study has to include patients with
different stages of the target disease. The study design is, again, the patient-control study
(selection of groups of patients with a known stage of the disease).
This document is made available for students merely for even better practice,
preparation and brainstorming purposes.
