Monitoring and Screening HINF Medical Methodologies Session 10

Objective Understand the function of screening and monitoring in the continuum of disease progression Understand the function of screening and monitoring in the continuum of disease progression Understand the factors in deciding for screening and monitoring Understand the factors in deciding for screening and monitoring

Reading Mar CD, Doust J, Glasziou (2006) Chapter 7: Monitoring in Chronic Disease, Blackwell Publishing and BMJ Books, USA Mar CD, Doust J, Glasziou (2006) Chapter 7: Monitoring in Chronic Disease, Blackwell Publishing and BMJ Books, USA Mar CD, Doust J, Glasziou (2006) Chapter 8: Screening for disease, health promotion and disease prevention, Blackwell Publishing and BMJ Books, USA Mar CD, Doust J, Glasziou (2006) Chapter 8: Screening for disease, health promotion and disease prevention, Blackwell Publishing and BMJ Books, USA

Quick discussion about assignment types possible 1. Current structure – questions and answers (4 of them) 2. Introduction of a case and development of the decision (one of two assignments for the term) 3. Data given for a health region and decisions for program development (single assignment for the term) 4. Student presentations of topics (considered one assignment)

Prevention and Screening Aim is to reduce the risk of death and morbidity by reducing the exposure to risk factors for disease before the process even starts (health promotion) or by providing interventions that prevent the disease from ever manifesting (disease prevention) – primary prevention Aim is to reduce the risk of death and morbidity by reducing the exposure to risk factors for disease before the process even starts (health promotion) or by providing interventions that prevent the disease from ever manifesting (disease prevention) – primary prevention

Levels of Prevention Activity What it does Examples Health promotion Interventions that generally improve health for everyone Exercise, stop smoking, eating well Disease prevention Pre-emptively acting before a specific disease manifests Vaccination, Seat belts, cycle helmets Disease screening Look signs of disease before they manifest Mammography, BP measurement, cervical screening Anticipatory care Looking for, and anticipating complications of a disease Db (retinopathy, micovascular damage, neuropathy), CHF (acute crisis, adherence to drugs, diet,exercise)

Screening Preferred - Pre-test probability is high and test is highly sensitive Preferred - Pre-test probability is high and test is highly sensitive Decision criteria for development Decision criteria for development Is the disease important? Is the disease important? Is there an effective test? Is there an effective test? Is there an effective treatment? Is there an effective treatment? Is the test affordable and acceptable? Is the test affordable and acceptable? Decision criteria for use Decision criteria for use Is the effective treatment more effective in early stages? Is the effective treatment more effective in early stages? Do benefits outweigh harms? Do benefits outweigh harms? Is the test routinely available? Is the test routinely available? Examples: Cervical cancer, prostate cancer, stroke, PKU, Lung Cancer Examples: Cervical cancer, prostate cancer, stroke, PKU, Lung Cancer

Selection of Population to Target High risk groups or all groups High risk groups or all groups High risk groups High risk groups Exposure to the risk factor is more limited within the population Exposure to the risk factor is more limited within the population Where susceptibility following exposure to the risk factor is limited, or where there is a threshold effect Where susceptibility following exposure to the risk factor is limited, or where there is a threshold effect Where it is easier or cheaper to identify persons at high risk Where it is easier or cheaper to identify persons at high risk Intervention is difficult to comply with or carries a significant risk of side effects Intervention is difficult to comply with or carries a significant risk of side effects All groups All groups The target disorder is common and a large proportion of the population is exposed to risk factors for target disorder The target disorder is common and a large proportion of the population is exposed to risk factors for target disorder Where the risk of disease rises continuously with exposure to the risk factor (as occurs with blood pressure and cholesterol levels) Where the risk of disease rises continuously with exposure to the risk factor (as occurs with blood pressure and cholesterol levels) Where it is easier or cheaper to apply an intervention to an entire population than to find and direct the interventions to individuals at high risk of the target disorder Where it is easier or cheaper to apply an intervention to an entire population than to find and direct the interventions to individuals at high risk of the target disorder

Monitoring Periodic measurement followed by adjustment of the management Periodic measurement followed by adjustment of the management External homeastasis External homeastasis Clinical effectiveness versus opportunity cost Clinical effectiveness versus opportunity cost

When to monitor What are the short-term consequences? What are the short-term consequences? What are the long term consequences? What are the long term consequences? Do symptoms give early warning? Do symptoms give early warning?

Phases of Monitoring Pre-treatment (to diagnose) Pre-treatment (to diagnose) Initial titration Initial titration Pharmacokinetics Pharmacokinetics Pharmacodynamics Pharmacodynamics Maintenance Maintenance One recording above 3 SD One recording above 3 SD Two recordings above 2 SD Two recordings above 2 SD Re-establish control Re-establish control Cessation Cessation

Which Measurement Is it a good measure of clinically relevant outcomes? Is it a good measure of clinically relevant outcomes? Proximal targets versus distal targets Proximal targets versus distal targets Can it detect changes in risk rapidly enough? Can it detect changes in risk rapidly enough? “Most relevant outcome that can be assessed reasonably soon” “Most relevant outcome that can be assessed reasonably soon” Is the random variability acceptable, or can it be made acceptable by repeated measurements? Is the random variability acceptable, or can it be made acceptable by repeated measurements? Is it sufficiently affordable, accessible, and acceptable to patients? Is it sufficiently affordable, accessible, and acceptable to patients?

Can it detect changes in risk rapidly enough? Patient adherence  drug concentration  markers of bone turnover  bone mineral density  asymptomatic factures  symptomatic fractures

Patient Monitoring For reporting to physician For reporting to physician For improving the adherence For improving the adherence For early warning For early warning For treatment adjustments? For treatment adjustments?

Common Errors in Monitoring Re-checking too soon Re-checking too soon Over-reacting to changes Over-reacting to changes Over-adjusting therapy Over-adjusting therapy