The “case-control” study: Valid selection of subjects

1985 ◽  
Vol 38 (7) ◽  
pp. 543-548 ◽  
Author(s):  
Olli S. Miettinen
Keyword(s):  
Case Control Study ◽  
Case Control ◽  
Control Study ◽  
Selection Of

α+-thalassemia protects African children from severe malaria

Blood ◽  
2004 ◽  
Vol 104 (7) ◽  
pp. 2003-2006 ◽  
Author(s):  
Frank P. Mockenhaupt ◽  
Stephan Ehrhardt ◽  
Sabine Gellert ◽  
Rowland N. Otchwemah ◽  
Ekkehart Dietz ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Natural Selection ◽  
Confidence Interval ◽  
Severe Malaria ◽  
High Frequency ◽  
Odds Ratio ◽  
Case Control Study ◽  
Case Control ◽  
Control Study ◽  
Selection Of

Abstract The high frequency of α+-thalassemia in malaria-endemic regions may reflect natural selection due to protection from potentially fatal severe malaria. In Africa, bearing 90% of global malaria morbidity and mortality, this has not yet been observed. We tested this hypothesis in an unmatched case-control study among 301 Ghanaian children with severe malaria and 2107 controls (62% parasitemic). In control children, α+-thalassemia affected neither prevalence nor density of Plasmodium falciparum. However, heterozygous α+-thalassemia was observed in 32.6% of controls but in only 26.2% of cases (odds ratio [OR], 0.74; 95% confidence interval [CI], 0.56-0.98). Protection against severe malaria was found to be pronounced comparing severe malaria patients with parasitemic controls (adjusted OR in children < 5 years of age, 0.52; 95% CI, 0.34-0.78) and to wane with age. No protective effect was discernible for homozygous children. Our findings provide evidence for natural selection of α+-thalassemia in Africa due to protection from severe malaria.

Selection of cases and controls in a case–control study

2008 ◽  
Vol 124 (3) ◽  
pp. 362-363
Author(s):  
Demosthenes B. Panagiotakos ◽  
Loukianos Rallidis ◽  
Christos Pitsavos ◽  
Christodoulos Stefanadis ◽  
Dimitrios Kremastinos
Keyword(s):  
Case Control Study ◽  
Case Control ◽  
Control Study ◽  
Selection Of

Selection of High-Risk Groups for Breast Cancer Screening. Evidence from an Italian Multicentric Case Control Study

1988 ◽  
Vol 74 (6) ◽  
pp. 675-679 ◽  
Author(s):  
Eugenio Pari ◽  
Marco Rosselli Del Turco ◽  
Domenico Palli ◽  
Eva Buiatti ◽  
Paolo Bruzzi ◽  
...  
Keyword(s):  
Logistic Model ◽  
Case Control Study ◽  
Risk Groups ◽  
Case Control ◽  
Logistic Analysis ◽  
Predicted Probability ◽  
Screening Population ◽  
Population Program ◽  
Control Study ◽  
Selection Of

In recent years techniques for the selection of risk groups for high priority breast screening have been evaluated (7, 11). We used data from a large multicentric case control study in Italy, recently published (12), to fit a reduced logistic model for predictive purposes, using variables which are easily collected. The predicted probability of being a case obtained through the logistic analysis was then used to classify the same set of data by calculating values of sensitivity and specificity at different cutoff points of the predicted probability. The results showed the low predictive power of the model. The selection of higher risk groups in a screening population program is discussed.

Sign in / Sign up

Export Citation Format

Share Document