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Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.
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One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs.We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs.We notice that the substitution of research population in place of a susceptible one can be used for effect estimation.Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline.The temporal precedence of exposure over outcome occurs theoretically,despite the opposite happens in realities.Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.
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The overall details of causality frames in the objective world remain obscure,which poses difficulty for causality research.Based on the temporality of cause and effect,the objective world is divided into three time zones and two time points,in which the causal relationships of the variables are parsed by using Directed Acyclic Graphs (DAGs).Causal DAGs of the world (or causal web) is composed of two parts.One is basic or core to the whole DAGs,formed by the combination of any one variable originating from each time unit mentioned above.Cause effect is affected by the confounding only.The other is an internal DAGs within each time unit representing a parent-child or ancestor-descendant relationship,which exhibits a structure similar to the confounding.This paper summarizes the construction of causality frames for objective world research (causal DAGs),and clarify a structural basis for the control of the confounding in effect estimate.
ABSTRACT
Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.
ABSTRACT
One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs.We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs.We notice that the substitution of research population in place of a susceptible one can be used for effect estimation.Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline.The temporal precedence of exposure over outcome occurs theoretically,despite the opposite happens in realities.Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.
ABSTRACT
The overall details of causality frames in the objective world remain obscure,which poses difficulty for causality research.Based on the temporality of cause and effect,the objective world is divided into three time zones and two time points,in which the causal relationships of the variables are parsed by using Directed Acyclic Graphs (DAGs).Causal DAGs of the world (or causal web) is composed of two parts.One is basic or core to the whole DAGs,formed by the combination of any one variable originating from each time unit mentioned above.Cause effect is affected by the confounding only.The other is an internal DAGs within each time unit representing a parent-child or ancestor-descendant relationship,which exhibits a structure similar to the confounding.This paper summarizes the construction of causality frames for objective world research (causal DAGs),and clarify a structural basis for the control of the confounding in effect estimate.
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Nearly all scientific studies explore causality,which will be met by directed acyclic graphs (DAGs).This paper systematically introduces graphic language,basic and interference rules of DAGs,and their applications into identifying research questions,understanding and undertaking research designs,guiding data analysis,classifying biases,etc.DAGs play key roles in causality studies.
ABSTRACT
Nearly all scientific studies explore causality,which will be met by directed acyclic graphs (DAGs).This paper systematically introduces graphic language,basic and interference rules of DAGs,and their applications into identifying research questions,understanding and undertaking research designs,guiding data analysis,classifying biases,etc.DAGs play key roles in causality studies.
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Objective To propose a method to calculate sample size for survival analysis in single-arm trials.Methods Through theoretical formula derivation,we provided sample size estimation method for survival analysis in single-arm trials.Monte-Carlo simulations using STATA software were conducted to obtain the empirical power,so as to verify the accuracy of the estimated sample size.Results Simulation results showed that,when α =0.025 and α =0.01,the power of the sample size calculated by the formula is in accordance with the predetermined power.Conclusions The formula of sample size estimation we proposed could achieve the predetermined power for survival analysis in single-arm trials.Findings of this study provide reliable basis for sample size estimation of early stage antineoplastic drug clinical studies.
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Objective To assess the prognosis and effect on renal function of pediatric urolithiasis caused by melamine-contaminated milk powder (PUMMP) in a long-term follow-up.Methods One hundred and two of 8335 children (≤ 6-year-old) with history of consuming melamine-contaminated milk powder screened in our hospital were followed up for eighteen months after diagnosis. Urinary system ultrasonography, urinalysis, urinary microprotein profiles [microalbumin (ALBU), immunoglobulin G (IgG), and N-acetyl-β-D-glucosidase (NAG)], urinary melamine and cyanuric acid were examined in the first visit and at the end of follow-up. Results Follow-up was completed in 91 children and the stone was excreted in 82 children (90.1%).Stones less than 5 mm in diameter were most vulnerable to discharge, and stones larger than 10 mm could not be expelled without interventions. At the end of follow-up, no melamine or cyanuric acid was found in the urine samples of 74 patients. Urinalysis showed that incidences of proteinuria, microscopic hematuria and leukocyturia were 0%, 5.1% and 2.0%, which were significant different from those in the first visit (Pproteinutria=0.123, Phemnatuna=0.038 and Pleukocyhuris=0.005).Urinary microprotein profiles revealed that some children whose urinalysis was normal still presented glomerular and renal tubular injury and the abnormal rates were 8.8% and 12.1%respectively. The glomerular injury was mainly related to persistent stone, male and younger.Conclusions 90.1% of children with PUMMP passes urinary stones at the end of follow-up.Stone size is the major risk factor of discharge. No melamine or cyanuric acid is found in the urine of children. After eighteen months, glomerular and renal tubular injury is still found in some patients. Further follow-up is necessary.
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Objective To understand the life quality of elderly person in communities, nursing homes and elderly wards, and to find out the related influencing factors for providing references for policy-makers to improve the life quality of the elderly. Methods The senior citizens in 9 communities, 3 villages, 12 nursing homes and 5 elderly wards in Shanghai Minhang District were enrolled by stratified cluster sampling. And the life quality and its influential factors among the inhabitants in communities, nursing homes and elderly wards were compared by adopting Short-Form 36 (SF-36) questionnaire. Results Regarding to the life qualities of senior citizens, community showed that physical functioning was (71. 9 ± 23. 3)scores, role physical was (73. 6 ± 43. 0) scores, bodily pain was (80. 2±20. 3)scores, general health was (53. 2± 19. 1)scores, vitality was (70. 4± 15. 7)scores, social function was ( 83. 8 ± 20. 2) scores, role emotional was ( 81. 1 ± 37. 2 ) scores, mental health was (78. 1 ± 15. 4) scores, weighted average was (74. 1 ± 17. 5) scores. Nursing home showed that physical functioning was (42. 1 ±30. 7) scores, role physical was (57. 9 ±48. 1) scores, bodily pain was (78.0±23.0)scores, general health was (50. 2± 19. 5)scores, vitality was (66. 0± 19. 5)scores, social function was (70. 8 ± 26. 3) scores, role emotional was (66. 8 ± 45. 7) scores, mental health was (73. 6 ± 19. 6) scores, weighted average was (63. 2 ± 21. 0) scores. Elderly ward showed that physical functioning was (20. 4 ± 26. 0) scores, role physical was (36. 1 ± 47. 0) scores, bodily pain was (65. 4±29. 5)scores, general health was (43. 1±17. 1)scores, vitality was (59. 0± 18. 0)scores, social function was (57. 9 ± 25. 3) scores, role emotional was (49. 5 ± 48. 7) scores, mental health was (66. 2 ± 18. 3) scores, weighted average was (49. 7 ±18. 3) scores. The major influential factors on the life quality were gender, education, marriage, profession, age, disease, residence, entertainment, physical exercise for community; Age, disease, residence, entertainment, physical exercise for nursing home; Age, etc for elderly ward. Conclusions The influences of demographic factors on life quality of the senior citizens in communities are more significant than in nursing home and elderly wards. Variations on the degree of satisfaction (in residence, entertainment, health care and transportation) and the situation of physical exercise have made vast difference in the life quality of the senior citizens both in communities and nursing homes.
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Objective To compare the value of clinical application of the ratio of urine albumin to creatinine (ACR) in the community-dwelled middle-aged and elderly at high-risk for diabetes in screening for albuminuria with casual and morning urine specimens. Methods Totally, 443 middle-aged and elderly people (234 men and 209 women) at high-risk for diabetes, with an average age of (59±8) years, were recruited from Changfeng Community of Shanghai in screening for albuminuria with casual and morning urine specimens collected on the same day, as well as another two morning urine specimens collected at an interval of two weeks, for determination of urine ACR. Albuminuria was defined as ACR equal to or more than 30 mg (albumin)/g (creatinnine) in two or more of the three urine specimens collected. Results Overall prevalence of albuminuria was 6. 3% ( 28/443 ) in the middle-aged and elderly according to diagnostic standard mentioned above, significantly higher in casual urine specimens than in morning urine specimens (14. 9% vs. 5.9%, P <0. 05). Urine ACR of casual urine specimens was significantly higher than that of morning urine (7. 1 mg/g vs. 3. 2 mg/g, P<0. 001 ). There was no significant difference in sensitivity and positive predictive value (PPV) between casual and morning urine specimens in screening for albuminuria (96. 4% vs. 92. 9%, and 99.7% vs. 99. 5%, respectively, P >0. 05). Specificity and negative predictive value (NPV) of casual urine specimens was significantly lower than those of morning urine specimens (90.6% vs. 100.0%, and 40.9% vs. 100.0%, respectively, P<0.05). The optimal cut-off value of ACR by casual urine specimens was 40. 0 mg/g in screening for albuminuria, based on receiver operating characteristic (ROC) curve, with sensitivity of 96. 4%, specificity 95.2%, PPV 57.5% and NPV 99. 8%. The middle-aged and elderly with negative albuminuria in morning urine but positive in casual urine had more risk factors for cardiovascular and chronic kidney diseases than those with negative albuminuria in both morning and casual urine specimens. Conclusions Morning urine specimen is better than casual urine for albuminuria screening in the middle-aged and elderly people with risk factors for diabetes in urban community, but casual urine used in screening for albuminuria is very convenient for collection. It is suggested that urine ACR of 40. 0 mg/g be used as an optimal cut-off value for casual urine in albuminuria screening among them.
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To develop an inquiry scale for diagnosis of heart system syndromes, and to discuss the provisional standardization of the inquiry method in traditional Chinese medicine (TCM).
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Objective To explore an optimal cut-off value of waist circumference(WC)for identifying metabolic syndrome(MS)in middle-aged and elder residents in an urban community.Methods Database of 1558 residents aged 40-79 years at high-risk in screening for diabetes from Changfeng community,Putuo District,Shanghai during 2005 to 2007 was used to analyze sensitivity and specificity of varied cut-off values of WC for identifying two or more components of MS in men and women,respectively.Receiver operating characteristics(ROC)curve was used to explore the optimal value.Results Optimal cut-off value of WC was 85.0 cm for men and 80.0 cm for women,respectively,for identifying two or more components of MS bv ROC curve,with sensitivity of 72.3%and 74.9%,and specificity of 50.2%and 62.2%,respectively.Based on that optimal cut-off value of WC and definition of International Diabetes Federation(IOF),prevalence of MS was 38.8%in this population,40.7%in men and 37.8%in women,respectively.Conclusion The optimal cut-off value of WC was 85.0 cm in men and 80.0 cm in women,respectively,for identifying MS in the middle-aged and eldedy in an urban community of Shanghai.
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<p><b>OBJECTIVE</b>To evaluate rates on the adverse side effect and discontinuation of second-line drugs frequently used in the treatment of rheumatoid arthritis (RA).</p><p><b>METHOD</b>Eight hundred and sixty-four RA patients were studied in a retrospective program.</p><p><b>RESULTS</b>Upper abdominal discomfort was most commonly seen when using second-line drugs. Rash was often associated with D-penicillamine (20.6%) and Sinomenium therapy (13.7%). Methotrexate (MTX) was uniquely characterized by substantial upper GI toxicity (32.2%) and Tripterygium wilfordii Hook. f. (TWH) (14.4%) by menstrual abnormality. Sulfasalazine users reported adverse events including upper abdominal trouble (39.0%), nausea (7.3%) and anorexia (7.3%) while the risk of GI malaise was greater. Patients taking hydroxychloroquine complained of blurred vision (19.6%) but no one went blind. Toxic side effects seemed to be the most common reasons for stoppages, and the patients taking MTX had the lowest discontinuation rate. Combination of D-penicillamine and Methotrexate did not increase the incidence of adverse events.</p><p><b>CONCLUSIONS</b>Knowledge on these different patterns of toxicity provided choices in the selection of second line agents for particular RA patients. However, long-term monitor are required when drugs are being used.</p>
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Anorexia , Antirheumatic Agents , Therapeutic Uses , Arthritis, Rheumatoid , Drug Therapy , Exanthema , Gastrointestinal Diseases , Hydroxychloroquine , Therapeutic Uses , Methotrexate , Therapeutic Uses , Nausea , Penicillamine , Therapeutic Uses , Phytotherapy , Plant Preparations , Therapeutic Uses , Retrospective Studies , Sinomenium , Sulfasalazine , Therapeutic UsesABSTRACT
<p><b>OBJECTIVE</b>To assess the effectiveness of an educational intervention program in sexually transmitted disease (STD) and condom-related knowledge and promoting condom use among STD patients.</p><p><b>METHODS</b>STD clinic patients were randomly assigned to three groups (A, control group; B, video viewing group; group C, video viewing plus education with talk) after administered with baseline questionnaire. Each patient was then scheduled to complete the questionnaire regarding the change of STD knowledge and use of condom in two weeks and 3 months.</p><p><b>RESULTS</b>Six hundred and forty-eight patients entered the study. More than half of the patients were aware of STD-related knowledge. However the rate of condom use was very low. When having intercourse with the casual sexual partners the percentage of condom use was only 20%. Seventeen per cent of the patients knew nothing about how to use condom correctly. Follow up results showed that the education program increased the knowledge about STD to some degree. However the percentage of condom use in the latest sexual intercourse increased greatly both in intervention and control groups, but more in intervention groups (P < 0.05).</p><p><b>CONCLUSION</b>STD education should be focused on advocating and correcting condom use.</p>
Subject(s)
Adult , Female , Humans , Male , Condoms , Health Knowledge, Attitudes, Practice , Health Promotion , Methods , Patient Education as Topic , Methods , Sexually Transmitted Diseases , Videotape RecordingABSTRACT
Objective Isosorbide-5-mononitrate(ISMN), a long-acting venous dilator,has been shown to decrease portal pressure and used in cirrhotic patients to prevent esophageal variceal bleeding(EVB). We performed a meta-analysis to evaluate ISMN in prevention of EVB. Methods Data from Medline(1968-2003), EMBASE(1986-2003), Cochrane Library(issue 3,2003),CJFD(1994-2003) were searched to retrieve randomized controlled trials comparing ISMN combined with or without other treatments to placebo or other treatments in prevention of EVB.Outcome measure was odds ratio( OR ) of bleeding rate. Mantel-Haeszel method was used in fixed model, while Der Simonian and Laird methods were used in random model. Results Seven trials were identified including prevention of first bleeding and rebleeding. The results of meta-analysis indicated that ISMN had no effect on prevention of EVB[study group vs control group: 88/463 vs 117/465, random model: OR (95% CI ): 0.63(0.37, 1.08 )]. Based on sensitivity analysis compared with control group, ISMN had no effect [43/314 vs 40/314, fixed model: OR :0.63(0.37, 1.08)]on prevention of first bleeding, but had therapeutic efficacy [45/149 vs 77/151, fixed model: OR :0.39 (0.24,0.65)]on prevention of rebleeding. Combination therapy of ISMN and ?-blocker revealed more effective than single therapy with ?-blocker[53/327 vs 74/329, fixed model: OR :0.64(0.42, 0.98)]in prevention of rebleeding [25/80 vs 41/81, fixed model: OR :0.44(0.23, 0.85 )], but had no significant difference in prevention of first bleeding[28/247 vs 33/248, fixed model: 0.84(0.48, 1.44)]. Conclusions ISMN is effective in prevention of esophageal variceal rebleeding. Furthermore , combination with ?-blockers has more therapeutic efficacy in prevention of esophageal variceal rebleeding.
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Objective To make the quality control of the tests used in the schistosomiasis survey. Methods A specific new method was proposed to test the independency of three tests in order to control the quality of the survey. Simulated data and real survey data were used to discuss the adaptability of the method. Results The simulated data and the real data both revealed that the new method could be used to test the independency of three tests. Conclusions The new approach can be applied in the quality control of schistosomiasis survey and is of high value for wide application.