Bài giảng Y học chứng cứ: Bài 5 - PGS.TS. Lê Hoàng Ninh

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Bài giảng Y học chứng cứ bài 5: Chứng cứ của các nghiên cứu chuẩn đoán, trình bày cơ sở chuẩn đoán, đánh giá các nghiên cứu chuẩn đoán, sai lầm trong chuẩn đoán, thiết kế cơ bản của một nghiên cứu chuẩn đoán chính xác. Đây là tài liệu tham khảo dành cho sinh viên và những ai đang hoạt động trong ngành Y.

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Nội dung Text: Bài giảng Y học chứng cứ: Bài 5 - PGS.TS. Lê Hoàng Ninh

Bài 5: CHỨNG CỨ CỦA CÁC NGHIÊN CỨU CHẨN ĐOÁN Matthew J. Thompson p GP & Senior Clinical Scientist Department of Primary Health Care University of Oxford
Nội dung bài học ộ g ọ Cơ sở chẩn đoán Đánh giá các nghiên cứu chẩn đoán
Chẩn đoán là gì? Làm tăng độ chắc chắn việc ắ ắ mắc hay không mắc bệnh Tính trầm trọng của bệnh Giám sát theo dỏi diển biến lâm sàng Đánh giá tiên lượng-nguy cơ/ g ợ g g y các giai đoạn của bệnh Kế hoạch điều trị Kịp lúc Knottnerus, BMJ 2002
Sai lầm trong chẩn đoán Hầu hết các sai lầm trong chẩn đoán là cognitive errors: Conditions of uncertainty Thinking is pressured Shortcuts are used (Ann Croskerry Ann Emerg Med 2003) Croskerry. Những sai lầm trong chẩn đoán (Diagnostic errors - The next frontier for Patient Safety. Newman-Toker, JAMA 2009) 40,000-80,000 40 000 80 000 US h hospital d th f it l deaths from misdiagnosis per year Adverse events, negligence cases, serious disability more likely to be related to misdiagnosis than drug errors
Diagnostic reasoning Diagnostic strategies particularly important where patients present with variety of conditions and possible diagnoses. p g
Diagnostic reasoning Thí dụ: nguyên nhân của ho là gì? Comprehensive history examination differential diagnosis final diagnosis
Diagnostic reasoning For example, what causes cough? Comprehensive histor e amination differential Comprehensi e history…examination…differential diagnosis…final diagnosis Cardiac failure left sided , Chronic obstructive pulmonary disease , Lung abscess failure, Pulmonary alveolar proteinosis, Wegener's granulomatosis, Bronchiectasis Pneumonia, Atypical pneumonia, Pulmonary hypertension Measles, Oropharyngeal cancer, Goodpasture's syndrome Pulmonary oedema, Pulmonary embolism, Mycobacterium tuberculosis Foreign body in respiratory tract, Diffuse panbronchiolitis, Bronchogenic carcinoma Broncholithiasis, Pulmonary fibrosis, Pneumocystis carinii Captopril, Whooping cough, Fasciola hepatica Gastroesophageal reflux, Schistosoma haematobium, Visceral leishmaniasis Enalapril, Pharyngeal pouch, Suppurative otitis media Upper respiratory tract infection, Arnold's nerve cough syndrome, Allergic bronchopulmonary aspergillosis Chlorine gas, Amyloidosis, Cyclophosphamide Tropical pulmonary eosinophilia, Simple pulmonary eosinophilia, Sulphur dioxide Tracheolaryngobronchitis, Tracheolaryngobronchitis Extrinsic allergic alveolitis Laryngitis alveolitis, Fibrosing alveolitis, cryptogenic, Toluene di-isocyanate, Coal worker's pneumoconiosis Lisinopril, Functional disorders, Nitrogen dioxide, Fentanyl Asthma, Omapatrilat, Sinusitis Gabapentin, Cilazapril ……diagnostic reasoning di ti i
Đánh giá test chẩn đoán g 1. Kết quả có giá trị? 2. 2 Kết quả gì? ả ì? 3. Kết quả đó có giúp chăm sóc bệnh nhân ó ệ â không?
Thiết kế cơ bản của một nghiên cứu chẩn đoán chính xác Hàng loạt bệnh nhân Chỉ số của test Tham chiếu tiêu chuẩn vàng ( gold”) standard Xếp loại bệnh nhân (Blinded cross- l cross-classification) ifi ti )
Validity of diagnostic studies y g 1. Was an appropriate spectrum of patients pp p p p included? 2. Were all patients subjected to the gold standard? 3. Was there an independent, blind or objective comparison with the gold standard? p g
1. Was an appropriate spectrum of pp p p patients included? Spectrum bias Selected Patients Index test Reference standard Blinded cross-classification cross-
1. Was an appropriate spectrum of patients included? Spectrum bias You want to find out how good chest X rays are for diagnosing pneumonia in the Emergency D E Department t t Best = all patients presenting with difficulty breathing t diffi lt b thi get a chest Xh t X-ray Spectrum bias = only those patients in whom you really suspect pneumonia get a h ll t i t chest X ray
2. Were all patients subjected to the gold standard? V ifi ti ( t d d? Verification (work-up) bi k ) bias Series of patients Index test Reference standard Blinded cross-classification cross-
2. Were all patients subjected t th gold 2 W ll ti t bj t d to the ld standard? Verification (work-up) bias You want to find out how good is exercise ECG (“treadmill test”) for identifying p ( ) y g patients with angina The gold standard is angiography Best = all patients get angiography Verification (work-up bi ) = only patients V ifi ti ( k bias) l ti t who have a positive exercise ECG get angiography angiograph
3. Was there an independent, blind or objective comparison with th gold bj ti i ith the ld standard? Observer bias Series of patients Index test Reference standard Unblinded cross-classification cross-
3. Was there an independent, blind or objective comparison with the gold j p g standard? Observer bias You want to find out how good is exercise ECG for identifying p y g patients with angina g All patients get the gold standard (angiography) Observer bias = the Cardiologist who does the angiography knows what the exercise ECG showed (not blinded)
Incorporation Bias Series of patients Index test Reference standard….. includes parts of Index test Unblinded cross-classification cross-
Differential Reference Bias Series of patients Index test Ref. Std A Ref. Std. B Blinded cross-classification cross-
Validity of diagnostic studies y g 1. Was an appropriate spectrum of patients pp p p p included? 2. Were all patients subjected to the Gold Standard? 3. Was there an independent, blind or objective p , j comparison with the Gold Standard?
Appraising diagnostic tests pp g g 1. Are the results valid? 2. Wh t 2 What are th results? the lt ? 3. Will they help me look after my patients?