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Outcome evaluation of screening

Outcome evaluation of screening. Wei-Chu Chie. Screening . Secondary prevention early detection and prompt treatment screening people with early, often preclinical, manifestations of diseases, to prevent its progression must followed by diagnosis and treatment procedures. Variants.

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Outcome evaluation of screening

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  1. Outcome evaluation of screening Wei-Chu Chie outcome research/screening

  2. Screening • Secondary prevention • early detection and prompt treatment • screening people with early, often preclinical, manifestations of diseases, to prevent its progression • must followed by diagnosis and treatment procedures outcome research/screening

  3. Variants • Mass screening • opportunistic screening • clinical case finding outcome research/screening

  4. Endpoints and efficacy evaluation • Compare the outcomes of screened and non-screened (symptomatic) groups • mortality • case-fatality/survival • total (overall) mortality • specific mortality • specific morbidity outcome research/screening

  5. Case-fatality/survival • Count from the time of diagnosis • take only causes of death that related to the target disease(s) of screening • lead-time bias • length bias (prognosis selection bias) outcome research/screening

  6. Overall mortality • Count from the time of participation • take all causes of death • unaffected by the ways of diagnosis or detection • overall impact of the program • positive & negative • sometimes insensitive outcome research/screening

  7. Specific mortality • Count from the time of participation • take only causes of death that related to the target disease(s) of screening • may be affected by the ways of diagnosis or detection • more sensitive • sometimes difficult to identify outcome research/screening

  8. Specific morbidity • Count from the time of participation • take only some severity indices of the target disease(s) of screening • stages, tumor size, certain complications, ... • not the final outcome • only surrogate in nature outcome research/screening

  9. Study design • Randomized controlled trial • non-randomized • cohort • case-control • other variants • meta-analysis outcome research/screening

  10. 實驗性方法的三要素 • 實驗單位 (experimental unit) • 處置 (treatment) • 評估 (evaluation) outcome research/screening

  11. 實驗單位 • 個人為單位 • 病人 • 藥物臨床試驗 • 教育介入 如病人衛生教育 • 健康人 • 疫苗預防性試驗 篩檢工具試驗 • 教育介入 如健康行為的養成 • 群體為單位 • 社區 班級 團體 outcome research/screening

  12. 處置 • 新藥 • 新的飲食 • 診斷或篩檢 • 手術 • 醫療器材 • 教育介入 • 無治療 outcome research/screening

  13. 評估 • 有效性 • 事件/事件史資料 (event/time to event) • well-being指標: 生活品質(quality of life) • 成本: 直接與間接醫療成本 • 暫時性或替代性指標: 生理 生化 病理資料 • 又稱終點 (end-points) • 安全性 • 不良反應及相關指標 • 經濟學: 成本效益 outcome research/screening

  14. Common problems • No blindness • screener • subjects • evaluator or rater • sometimes randomized by cluster for the convenience of intervention • statistical help outcome research/screening

  15. Examples • Breast self-examination for breast cancer • mass screening • General health screening for cardiovascular risks • by general practitioners • Case-finding for depression in primary care • by general practitioners outcome research/screening

  16. BSE • Thomas DB., et al. Randomized trial of breast self-examination in Shanghai: final results. JNCI 2002; 94:1445-1457. outcome research/screening

  17. BSE: background/goal/hypothesis • Background: • BSE efficacy unproven • Goal: • to determine whether ... • Hypothesis: • an intensive program of BSE instruction will reduce the mortality (number of death ) of breast cancer outcome research/screening

  18. BSE: study design • Randomized controlled trial • instruction group • control group • randomized by cluster (factories) stratified by hospital affiliation • no statistical adjustment: large number and identical rates • mass screening outcome research/screening

  19. BSE: subjects • Shanghai Textile Industry Bureau (STIB) employees • women born between 1925-1958 (31-64) • eligibility, inclusion/exclusion criteria • 289292 ….266064 • instruction: 146437 …. 132979 • control: 142955 …. 133085 outcome research/screening

  20. BSE: exposure/intervention • BSE instruction • small group (10) • video/practice/discussion/reinforcement • review/supervision • proficiency assessment outcome research/screening

  21. BSE: endpoint • Primary: death from breast cancer • definition • judgement: blind • Secondary? • Intermediate variables: benign tumors/biopsies • Follow-up: 11 years outcome research/screening

  22. BSE:data analysis • Survival • from time of entry • from time of diagnosis • Kaplan-Meier/log-rank test • Cox proportional hazards model • comparability , compliance, … • intermediate variables outcome research/screening

  23. BSE: major results/discussion • Mortality/survival • from entry • from diagnosis • comparability, compliance, … • intermediate variables • benign tumors … biopsy (unnecessary burden) outcome research/screening

  24. CRS • Engberg M., et al. General health screenings to improve cardiovascular risk profiles: a randomized controlled trial in general practice with 5-year follow-up. J Family Practice 2002;51:546-552. outcome research/screening

  25. CRS: background/goal/hypothesis • Background: Danish trial • GP’s role in primary prevention for CVD • Goal: • to investigate the impact of general health screenings and health discussions on CV risk profiles • Hypothesis: • … can reduce ... outcome research/screening

  26. CRS: study design • Randomized controlled trial • 3 groups • by individual • stratified randomization based on • GP, sex, age, cohabitation status, BMI • too many cells • GP X sex X age X … • stratified factors should be treated as covariates outcome research/screening

  27. Stratified randomization • Individuals stratified by certain characteristics • Independent random assignment to different groups in each cell • eg. Old-male, old-female, young-male, … • random code for each consecutive subject • can be generated by computer • To avoid imbalance • may have empty cells if N is small • no need when N is large outcome research/screening

  28. CRS: subjects • Ebeltoft, Aarhus County, Denmark • 9 GPs (general practitioners) • 3464 … random sample 2000 inhabitants • 30-49 years outcome research/screening

  29. CRS: exposure/intervention • Health screening & follow-up discussion • Group 1: health screening (502) • Group 2: health screening+follow-up discussion (504) • Group 3: none (control) (501) • All three: questionnaire outcome research/screening

  30. CRS: endpoint • Primary: score and categorical (high/low) • CRS: gender, family inheritance (CAD <55 y), tobacco use, BP, total serum cholesterol, BMI • BMI, SBP, DBP, serum cholesterol • by smoking and overweight subgroup analysis • No blindness • Follow-up: 5 years outcome research/screening

  31. CRS:data analysis • T-test, chi-square, … • intention-to-treat • compare values or high score rates instead of changes from baseline • endpoints • baseline data • follow-up rates outcome research/screening

  32. CRS:major results/discussion • CRS, BMI, and serum cholesterol levels were lower in the Intervention group • subgroup analysis: high vs. low risk ones • no differences between two intervention groups • not followed to the final endpoint outcome research/screening

  33. Depression • Williams JW. , et al. Case-finding for depression in primary care: a randomized trial. Am J Med 1999; 106: 36-43. outcome research/screening

  34. Dep: background/goal/hypothesis • Background: • impact of depression/role of primary care • Goal: • evaluate the efficacy of two case-finding instruments vs. usual care • Hypothesis: • … can enhance symptom reduction/recovery for depression patients outcome research/screening

  35. Dep: study design • Randomized controlled trial • 3 groups • by individual • random assignment stratified by site • computer-generated randomization blocked log outcome research/screening

  36. Dep: subjects • GP and internal medicine clinics in San Antonio, Texas and Washington, DC. • Consecutive adult patients • Only those diagnosed as with depression were analyzed • screened with case-finding: positive---additional questioning for clinical depression • all patients: DSM-III-R, CAGE, SF-36, satisfaction • rater (evaluator) blindness outcome research/screening

  37. Dep: exposure/intervention • Case-finding instruments screening • Group 1: single question (330) • Group 2: 20 item questionnaire (323) • Group 3: usual care (control) (316) outcome research/screening

  38. Dep: endpoint • Primary: only depressive patients • recovery rates (<=1 DSM-III-R symptoms) • symptoms score changes from baseline • Secondary: • satisfaction • Follow-up: 3 months outcome research/screening

  39. Dep:data analysis • Proportion and rates • Symptom numbers • only for patients diagnosed as with depressions • not severity indices • by medical record: counseling, referral, medicine • baseline data • follow-up rates outcome research/screening

  40. Dep:major results/discussion • Recovery rate: • case-finding better than usual care • symptoms numbers • not different • Only diagnosed patients were analyzed • not followed to the final endpoint outcome research/screening

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