A case control study is a type of observational study. In this study design, participants are selected to participate depending on their outcome status. Cases are participants with outcome of interest whereas controls are participants who do not have the outcome of interest. These studies estimate the odds ratio or the odds between the exposure and health outcome, however they cannot prove causality. Advantages of case control studies include the following: inexpensive, easy to design and implement, and are used to study rare outcomes. Case control studies are prone to certain research bias but can be addressed by the investigator through careful designing and planning. This paper describes the case control studies, their advantages, bias in case control studies and how to address them, and discuss the steps in how to conduct this type of study design.

Objective To investigate the effect of systematic graded rewarming pattern on all-cause mortality of hypothermic trauma patients in different time periods. Methods A prospective case-control study was carried out for 236 hypothermic trauma patients with modified trauma score<12 in the Emergency Department of the Second Affiliated Hospital of Wenzhou Medical University from January 2020 to December 2021.The patients were randomly assigned into a systematic graded rewarming group (n=118) and a traditional rewarming group (n=118).The main outcome event was all-cause death within 15 days after trauma,and the secondary outcome event was all-cause death within 3,7,and 30 days after trauma. Results Overall,13.98%(33/236) and 14.83%(35/236) of the patients died within 15 and 30 days after trauma,respectively,and the median survival time of all dead patients was 6 (4,10) days.The systematic graded rewarming group had higher temperature after rewarming for 2 h (P=0.001) and larger temperature change after rewarming intervention (P=0.047) than the traditional rewarming group.The all-cause mortality within 15 days (27.3%vs.72.7%,P=0.005) and 30 days (25.7%vs.74.3%,P=0.002) in the systematic graded rewarming group was lower than that in the traditional rewarming group.Kaplan-Meier analysis showed that the survival time of the patients in the systematic graded rewarming group was longer than that in the traditional rewarming group (P=0.003).Multivariate cox regression analysis indicated that systematic graded rewarming was a strong protective factor for survival time after trauma (HR=0.450, P=0.042).Further Logistic regression analysis for the occurrence of all-cause death in each time period showed that the OR of systematic graded rewarming pattern to all-cause death within 15 days and 30 days after trauma were 0.289 and 0.286,respectively,after adjusting the covariates(P=0.008,P=0.005).The temperature after rewarming for 2 h had a negative correlation with all-cause mortality within 30 days after trauma (OR=0.670, P=0.049). Conclusions Systematic graded rewarming is a protective factor for the survival time of patients with traumatic hypothermia and an independent factor affecting the risk of all-cause death within 15 days and 30 days after trauma.The temperature after rewarming for 2 h is expected to be an independent predictor of all-cause mortality of 30 days after trauma in the patients with hypothermia.The systematic graded rewarming pattern could reduce the mortality of hypothermic trauma patients.
Humans ; Hypothermia ; Rewarming ; Case-Control Studies

Objective To explore the relationship between scavenger receptor class B member 1 (SCARB1) gene promoter methylation and the pathogenesis of coronary artery disease. Methods A total of 120 patients with coronary heart disease treated in Renji Hospital affiliated to Shanghai Jiao Tong University School of Medicine from December 2018 to May 2020 were selected as the case group,while 140 gender and age matched healthy participants were randomly selected as the control group for a case-control study.The methylation status was detected by high-throughput target sequencing after bisulfite converting,and the methylation of CpG sites in the promoter region of SCARB1 gene was compared between the two groups. Results The case group showed higher methylation level of SCARB1+67 and lower methylation level of SCARB1+134 than the control group (both P<0.001),and the differences remained statistically significant in men (both P<0.001) and women (both P<0.001).The overall methylation level in the case group was lower than that in the control group [(80.27±2.14)% vs.(81.11±1.27)%;P=0.006],while this trend was statistically significant only in men (P=0.002). Conclusion The methylation of SCARB1 gene promotor is associated with the pathogenesis and may participate in the occurrence and development of coronary heart disease.
Male ; Humans ; Female ; Methylation ; Case-Control Studies ; China ; Coronary Artery Disease/genetics* ; Promoter Regions, Genetic ; DNA Methylation ; Scavenger Receptors, Class B/genetics*

Clinical efficacy is the basis for the development of traditional Chinese medicine(TCM), and the evaluation of clinical efficacy of TCM has always been the focus of attention. The technical and methodological difficulties in the evaluation process often restrict the generation of high-level evidence. Therefore, methodological research should be deepened and innovative practice should be carried out to study the application of scientific research methods in the evaluation of the advantages of TCM. After more than ten years of development, the clinical efficacy evaluation of TCM, on the basis of the initially classic placebo randomized controlled trials, has successively carried out a series of meaningful attempts and explorations in N-of-1 trials, cohort studies, case-control studies, cross-sectional studies, real world studies, narrative medicine studies, systematic evaluation, and other aspects, laying the foundation for the transformation of TCM from "experience" to "evidence". This paper focused on the clinical efficacy evaluation of TCM, summarized the main connotation and development status of efficacy evaluation indicators, standards, and methods, and put forward corresponding countermeasures and suggestions for the problems of indicator selection, standard formulation, and methodology optimization in the research process. It is clear that scientific and objective evaluation of the efficacy of TCM is an urgent problem to be solved at present.
Medicine, Chinese Traditional ; Cross-Sectional Studies ; Treatment Outcome ; Case-Control Studies ; Narrative Medicine

Objective: To investigate the clinical characteristics of Aspergillus fumigatus(A.f)-sensitized asthma and allergic bronchopulmonary aspergillosis (ABPA), which provides a foundation for the diagnosis and differential diagnosis of A.f-sensitized asthma and ABPA, as well as the prevention of ABPA. Methods: This was a single-center retrospective case-control study. Collected the clinical data of patients who visited the Department of Respiratory and Critical Care Medicine, Zhongnan Hospital of Wuhan University from December 2018 to May 2022.A total of 122 patients were included, including 64 males (52.5%) and 58 females (47.5%).The age range was 3 to 89 years.The median age was 44 years.The average age was 41.8 years.The patients were divided into three groups (48 ABPA, 35 A.f-sensitized asthma and 39 HDM-sensitized asthma).Analyzed the differences and correlations among clinical indicators in the three groups, and evaluated the risk factors for the development of ABPA in A.f-sensitized asthma.For statistical analysis, metrological data was tested by t-test or Wilcoxon Mann-Whitney. Classification variables by chi-square test or Fisher's exact test. Pearson correlation analysis for normal distribution data.Spearman correlation analysis for skewed distribution data. Influencing factor analysis was performed using multivariate logistic regression analysis. The receiver operating characteristic (ROC) curve was made, the area under the ROC curve (AUC) was calculated, and the sensitivity and specificity of the model were evaluated. Results: Compared with patients with A.f-sensitized asthma, the fractional exhaled nitric oxide (FeNO) [75.00(52.00, 87.00)ppb vs. 40.00(32.00, 52.00)ppb], eosinophils% (EO%) [10.60(6.75, 13.05) vs. 4.10(1.20, 7.30)], eosinophils (EO) [1.50(1.07, 2.20)×10⁹/L vs. 0.33(0.10, 0.54)×10⁹/L], A.f-specific Immunoglobulin E (sIgE) [10.24(4.09, 22.88)KU/L vs. 1.13(0.53, 3.72) KU/L], and sIgE to total IgE(tIgE) ratio (sIgE/tIgE) [0.0049(0.0027, 0.0100) vs. 0.0008(0.0004, 0.0017)] were higher in ABPA patients, the differences were statistically significant (P<0.001). In all patients, tIgE was positively correlated with EO% (r=0.206, P<0.05) and EO (r=0.302, P<0.001). sIgE/tIgE was negatively correlated with one-second rate (FEV1/FVC%) (r=-0.256, P<0.01). The percentage of predicted forced vital capacity [FVC(%)] was negatively correlated with FeNO (r=-0.184, P<0.05).In the ABPA group, the percentage of predicted peak expiratory flow [PEF(%)] was negatively correlated with FeNO (r=-0.295, P<0.05). In the HDM-sensitized asthma group, FeNO was positively correlated with EO% (r=0.49, P<0.01) and EO (r=0.548, P<0.001).The results of logistic regression analysis showed that FeNO and EO were the influencing factors for the development of ABPA in A.f-sensitized asthma. ROC curve analysis results showed that A.f-sIgE (cut-off, 4.108; AUC=0.749;95%CI, 0.632-0.867), sIgE/tIgE(cut-off, 0.0026;AUC=0.749;95%CI, 0.631-0.868), FeNO(cut-off, 55.5;AUC=0.794; 95%CI, 0.687-0.900), EO% (cut-off, 8.70;AUC=0.806;95%CI, 0.709-0.903) and EO (cut-off, 0.815;AUC=0.865;95%CI, 0.779-0.950) had differential diagnostic value in A.f-sensitized asthma and ABPA.The combination of FeNO, EO and EO% had good diagnostic efficiency in differentiating A.f-sensitized asthma from ABPA, with a sensitivity of 91.4% and a specificity of 84.4%. Conclusion: Compared with patients with A.f-sensitized asthma, patients with ABPA have more severe eosinophil inflammation. The higher the FeNO and EO, the more likely A.f-sensitized asthma will develop into ABPA.sIgE/tIgE may have differential diagnostic value in A.f-sensitized asthma and ABPA.The combination of FeNO, EO and EO% has good diagnostic efficacy in differentiating A.f-sensitized asthma from ABPA.
Male ; Female ; Humans ; Adult ; Child, Preschool ; Child ; Adolescent ; Young Adult ; Middle Aged ; Aged ; Aged, 80 and over ; Aspergillus fumigatus ; Retrospective Studies ; Case-Control Studies ; Aspergillosis, Allergic Bronchopulmonary/diagnosis* ; Asthma/diagnosis* ; Immunoglobulin E ; Nitric Oxide

Objective: To investigate the association of circulating sPD-1 level and PD-1 gene polymorphisms with HBV infection and HBV infection-associated hepatocellular carcinoma. Methods: A case-control study was conducted. A total of 237 chronic HBV infection cases and 138 HBV infection-associated hepatocellular carcinoma in the Department of Infectious Diseases of the First Hospital of Shanxi Medical University from 2018 to 2021 were selected as the case group. About 250 individuals who visited a hospital physical examination center for routine physical examination during the same period were selected as the control group. Plasma sPD-1 levels were measured by using an ELISA kit and genotyping was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The association of sPD-1 levels and PD-1 polymorphisms with HBV infection as well as HBV infection-associated hepatocellular carcinoma was analyzed by using logistic regression models after adjusting for age, sex, alcohol consumption, smoking, ALT and AST levels. The sPD-1 level and PD-1 polymorphisms were independent variables, and HBV infection was the dependent variable. Results: The age of 237 chronic HBV infections, 138 HBV infection-related liver cancer case subjects and 250 control subjects in the study was (49.1±10.8), (51.9±12.7) and (50.7±11.9) years, respectively. Multivariate logistic regression model analysis showed that with a 1 pg/ml increase in sPD-1 level, the OR (95%CI) values for the risk of incident HBV infection cases and HBV hepatocellular carcinoma cases were 1.92 (1.68-2.19) and 2.02 (1.69-2.40). For rs2227981, compared with the CC genotype, the TT genotype had a lower risk of HBV infection and liver cancer associated with HBV infection, with OR (95%CI) values of 0.45 (0.22-0.91) and 0.35 (0.14-0.91). For rs2227982, compared with the CC genotype, the CT and TT genotypes also had a lower risk of HBV infection [OR (95%CI) values of 0.72 (0.53-0.97) and 0.57 (0.35-0.93)] and HBV infection-related liver cancer [OR (95%CI) values of 0.64 (0.45-0.92) and 0.52 (0.29-0.93)]. Conclusions: Plasma sPD-1 levels and PD-1 gene polymorphisms are associated with HBV infection and HBV infection-associated hepatocellular carcinoma.
Humans ; Carcinoma, Hepatocellular/genetics* ; Case-Control Studies ; Genetic Predisposition to Disease ; Genotype ; Hepatitis B virus/genetics* ; Liver Neoplasms/genetics* ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Programmed Cell Death 1 Receptor/genetics* ; Adult ; Middle Aged

Objective: To evaluate the effect of inactivated SARS-CoV-2 vaccine on the clinical outcomes of patients infected with the Omicron variant. Methods: A total of 1 403 Omicron-infected patients admitted to 20 designated hospitals in Guangdong Province from January 1 to May 31, 2022, were selected as subjects in this study. A case-control study was conducted to collect the demographic data, underlying disease, vaccination status, last exposure date, gene sequencing of infected strains and clinical outcomes from the China Disease Prevention and Control Information System and Guangdong telemedicine platform. Pneumonia (common, severe and critical) and non-pneumonia (asymptomatic and mild) were selected as the case group and control group. The effect of inactivated SARS-CoV-2 vaccine on the clinical outcomes of patients infected with the Omicron variant was analyzed. Results: The median age [M (Q₁, Q₃)] of the subjects was 36 (27-47) years old, with males accounting for 52.25% (733 cases). The main outcome of the infection was non-pneumonia, accounting for 92.09% (1 292 cases), and the duration [M (Q₁, Q₃)] of the disease was 18 (14-22) days. There were 134 (9.55%), 39 (2.78%), 403 (28.72%), 437 (31.15%) and 390 (27.80%) cases with no or partial vaccination, within 90 days of primary vaccination, over 90 days of primary vaccination, within 90 days of booster vaccination and over 90 days of booster vaccination, respectively. Multivariate logistic regression analysis showed that after adjusting for gender, age, underlying disease, and location of the report, compared with those with no or partial vaccination, the risk of developing pneumonia was lower in those with over 90 days of primary vaccination, within 90 days of booster vaccination and over 90 days of booster vaccination [OR (95%CI) values were 0.52 (0.28-0.98), 0.39 (0.21-0.73) and 0.40 (0.21-0.77), respectively]. Cox proportional hazard regression model analysis showed that after adjusting for gender, age, underlying disease and location of the report, the duration of the disease was shorter in those who received booster vaccinated for more than 90 days compared with that in those who had no or partial vaccination [HR (95%CI): 1.26 (1.03-1.55)]. Conclusion: The inactivated SARS-CoV-2 vaccine affects the clinical outcomes of patients infected with the Omicron variant.
Adult ; Humans ; Male ; Middle Aged ; Case-Control Studies ; China/epidemiology* ; COVID-19/prevention & control* ; COVID-19 Vaccines ; SARS-CoV-2 ; Female

Objective: To investigate the relationship between the levels of selenium, iron and copper in cord blood of neonates and the risk of congenital heart disease (CHD), and analyze their interaction effects. Methods: The subjects were obtained from the birth cohort in Lanzhou area established from 2010 to 2012. A baseline survey was conducted in the first trimester, and the follow-up was conducted in the second trimester, third trimester and 42 days after delivery. The umbilical vein blood was collected from newborns at delivery, and information on their birth outcomes was extracted from medical records. A nested case-control study was used to select 97 neonates with CHD newly diagnosed by echocardiography as the case group, and 194 neonates were selected as the control group by 1∶2 matching according to their mother's age, block and CHD onset time. Inductively coupled ion mass spectrometry was used to detect the concentrations of selenium, iron and copper in neonatal cord blood. The element exposure was categorized into three groups, the low, medium and high concentrations, according to the quartiles Q₁ and Q₃ of selenium, iron and copper concentrations in the control group. The association between cord blood selenium, iron and copper concentrations and CHD was analyzed by conditional logistic regression model using medium concentration as the reference standard. The association of their interactions with CHD was analyzed by a phase multiplication model. Results: The M (Q₁, Q₃) concentration of neonatal cord blood copper was 746.12 (467.48, 759.74) μg/L in the case group and 535.69 (425.21, 587.79) μg/L in the control group, with a statistically significant difference between the two groups (P<0.05). After adjustment for confounders, logistic regression models showed that the risk of CHD development was increased in neonates with either high copper in cord blood (OR=4.062, 95%CI: 2.013-8.199) or high copper combined with high iron (OR=3.226, 95%CI: 1.343-7.750). No correlation was observed between selenium and iron concentrations and the development of CHD in neonates. There was a multiplicative interaction between copper and iron in cord blood on the risk of developing CHD (OR=1.303, 95%CI: 1.056-1.608). Conclusion: There is a multiplicative interaction between iron and copper elements. The high copper and the high copper combined with high iron in umbilical cord blood are risk factors for neonatal CHD.
Humans ; Infant, Newborn ; Copper/analysis* ; Selenium ; Iron/analysis* ; Fetal Blood/chemistry* ; Case-Control Studies ; Heart Defects, Congenital

Objective: To analyze associated factors and adverse pregnancy outcomes of postpartum hemorrhage in the caesarean section of puerperae with different types of placenta previa. Methods: This retrospective research was a case-control study. Puerperae with cesarean section of placenta previa from January 2019 to December 2020 in Women's Hospital, School of Medicine, Zhejiang University were collected and divided into the<1 000 ml control group or ≥1 000 ml postpartum hemorrhage group according to the amount of blood loss during cesarean section. Differences in continuous variables were analyzed by t-test and categorical variables were analyzed by χ² test. The risk factors of postpartum hemorrhage were analyzed by logistic multivariate regression. Results: A total of 962 puerperae were enrolled with 773 cases in the control group and 189 cases in the postpartum hemorrhage group. The incidence of gestational weeks, gravidity, parity, induced abortion, placental accreta and preoperative hemoglobin<110 g/L was significantly different between two groups in different types of placenta previa (P<0.001). Logistic multivariate regression model analysis showed that the independent risk factors of postpartum hemorrhage in the caesarean section of low-lying placenta included placental accreta (OR=12.713, 95%CI: 4.296-37.625), preoperative hemoglobin<110 g/L (OR=2.377, 95%CI: 1.062-5.321), and prenatal vaginal bleeding (OR=4.244, 95%CI: 1.865-9.656). The independent risk factors of postpartum hemorrhage in the caesarean section of placenta previa included once induced abortion (OR=2.789, 95%CI:1.189-6.544), induced abortion≥2 (OR=2.843, 95%CI:1.101-7.339), placental accreta (OR=6.079, 95%CI:3.697-9.996), HBsAg positive (OR=3.891, 95%CI:1.385-10.929), and placental attachment to the anterior uterine wall (OR=2.307, 95%CI:1.285-4.142). The rate of postpartum hemorrhage and premature delivery in puerperae with placenta previa was higher than that in puerperae with low-lying placenta (P<0.001). Conclusions: The associated factors of postpartum hemorrhage in puerperae with different types of placenta previa are different. Placenta accreta is the common risk factor of postpartum hemorrhage in puerperae with low-lying placenta and placenta previa.
Female ; Pregnancy ; Humans ; Cesarean Section ; Postpartum Hemorrhage/surgery* ; Pregnancy Outcome ; Retrospective Studies ; Case-Control Studies ; Placenta Previa/surgery* ; Placenta ; Risk Factors

Objective: Exploring the neuropsychological developmental characteristics and influencing factors of children with speech disorder. Methods: A case-control study was conducted. A total of 395 children diagnosed with speech disorders were selected as speech sound disorder (SSD) group from January 2019 to September 2021 in the speech-speech outpatient department of the Children's Hospital Affiliated to Capital Institute of Pediatrics, and 1 179 healthy children who underwent physical examination in the health department during the same period were selected as the control group. All the children were examined by the "Children's Neuropsychological Behavior Scale 2016 Edition" (Children's Mind Scale 2016 edition). Independent sample t test was used to compare the developmental levels of the two groups of children, including total developmental quotient, gross motor, fine motor, adaptive ability, language and social behavior ability. The influential factors of children's speech disorders were analyzed by univariate Chi-square analysis and multivariate logistic regression. Results: There were 395 SSD children, including 296 males and 99 females, 4≤ age ≤6, (4.71±0.76) years. There were 1 179 children in the control group, including 864 males and 315 females, 4≤ age ≤6, (4.64±0.78) years. The mean value of total developmental factors in SSD group was lower than that in control group [(86.45±11.57)/(91.24±8.0), t=-7.78, P<0.01], and the mean values of total developmental markers in both boys and girls in SSD group were lower than those in control group [(86.00±11.40)/(90.78±7.86), t=-6.70, P<0.01; (87.82±12.03)/(92.87±8.49), t=-3.88, P<0.01]. The mean values of gross motor, fine motor, adaptive ability, language ability and social behavior in SSD group were lower than those in control group [(89.76±12.47)/(92.01±10.69), t=-3.21, P<0.01; (80.62±13.64)/(84.49±11.55), t=-5.06, P<0.01; (87.92±15.25)/(92.98±12.06), t=-6.00, P<0.01; (86.48±16.30)/(94.55±12.08), t=-9.04, P<0.01; (87.02±15.18)/(92.63±12.57), t=-6.62, P<0.01]; The mean value of fine motor in boys was lower than that in girls in SSD group [(79.80±13.42)/(83.08±14.05), t=-2.08, P<0.05]. Independent mealtimes. 2 years old (OR=1.527, 95%CI: 1.180-1.977, P=0.001), delay in adding supplemental food (OR=1.510, 95%CI: 1.123-2.029, P=0.006), dialect in the home language environment (OR=1.351, 95%CI: 1.060-1.723, P=0.015) were risk factors for children with speech disorders. Conclusion: Children with speech disorders are more common in boys. The overall development level of SSD children is lower than that of normal children, and the fine motor of SSD boys is lower than that of girls. The incidence of children's speech disorders is related to the addition time of supplementary food, independent meal time and family language environment.
Male ; Female ; Child ; Humans ; Child, Preschool ; Speech Sound Disorder/diagnosis* ; Case-Control Studies ; Speech Disorders ; Cognition