HLTH 207 Week 4 Asynchronous Work (ONE)

Risk (exposed) calculation based on 2×2 table

 A/N1 = number of incident cases in an exposed at-risk population during a follow-up period/number of individuals in the exposed at-risk population at the beginning of the follow-up period

Risk (unexposed) calculation based on 2×2 table

B/N0 = number of incident cases in an unexposed at-risk population during a follow-up period/number of individuals in the unexposed at-risk population at the beginning of the follow-up period

Risk ratio calculation

risk in the exposed/risk in the unexposed = (A/N1)/(B/N0)

Risk ratio interpretation structure

The [length of follow-up] risk of the outcome in the exposed is RR times the risk of the outcome in the unexposed

Risk difference calculation

risk in the exposed - risk in the unexposed = (A/N1) - (B/N0)

Risk difference interpretation structure

The difference in the  [length of follow-up] risk of the outcome in the exposed versus the unexposed is RD

Positive risk difference interpretation

the risk is higher among those who are exposed (the additional/excess risk of an outcome due to exposure)

Negative risk difference interpretation

the risk is lower among those who are exposed (the reduction in risk of an outcome due to exposure)

Rate (exposed) calculation

A/PT1 = number of incident cases in an exposed at-risk population during a follow-up period/person-time contributed by those in the exposed at-risk population during the follow-up period

Rate (unexposed) calculation

B/PT0= number of incident cases in an unexposed at-risk population during a follow-up period/person-time contributed by those in the unexposed at-risk population during the follow-up period

Rate ratio (IDR) calculation

 rate in the exposed/rate in the unexposed = (A/PT1)/(B/PT0)

Rate ratio interpretation structure

The rate of the outcome in the exposed is IDR times the rate of the outcome in the unexposed

Rate difference (IDD) calculation

rate in the exposed - rate in the unexposed = (A/PT1) - (B/PT0)

Rate difference interpretation structure

The difference in the rate of the outcome in the exposed versus the unexposed is IDD

2 types of analysis

1. Intention to treat

2. Per protocol

Effectiveness

measures the ability of an intervention to prevent or treat the outcome among those randomized, whether or not they actually adhere to the assigned trial arm

What does effectiveness esimtae?

Estimates the benefit of an intervention closer to a real-world setting

Analysis type used when assessing effectiveness

Intention-to-treat - includes all randomized individuals, regardless of their adherence to their assigned trial arm

Efficacy

measures the ability of an intervention to prevent or treat the outcome only among those who adhere to their assigned trial arm

What does efficacy estimate?

Estimates the true etiologic benefit of an intervention

Analysis type used when assessing efficacy

Per-protocol - only includes individuals with perfect adherence to their assigned trial arm

An intervention that is not efficacious ________ (can/cannot) be effective

cannot

What 2 substances does the FDA regulate?

1. Prescription drugs

2. OTC drugs

When/at what stage does the drug testing process begin

The process begins at the preclinical phase with in vitro or in vivo animal model studies

Phase 0 of clinical phase of drug testing

evaluate pharmacokinetics and pharmacodynamics among smaller numbers of healthy participants

Phases I, II, and III of clinical phase of drug testing

evaluate safety, side effects, efficacy, and effectiveness among progressively larger number of healthy participant and progressing to larger groups including those who may have the condition or be at risk for the outcome

Phase IV of clinical phase of drug testing

occur after FDA approval and can include an even larger number of participants, find new markets, and assess longer-term outcomes

Randomization ethics principle

It is not ethical to randomize participants to receive exposures known to be harmful

Epiquoise definition and should a trial have it?

• the interventions tested should not already be known to be inferior or superior relative to control prior to the trial

• Yes, a study should have this

Protocol for a controlled trial in relation to harm vs. benefit principle

The protocol for a controlled trial should include stopping rules to halt the trial when risks outweigh benefits, there is not enough statistical power, and/or when the benefit or inferiority of the intervention is established

What 2 issues should be considered when conducting trials in underserved population?

1. Literacy

2. Coercion

There is a debate about whether trial participants should be receive _________________________ after the trial

guarenteed access to beneficial interventions

What type of reporting guidance is an accepted standard way to report clinical trials?

CONSORT reporting guidance

4 strengths of controlled trials

1. Temporarily between exposure and outcome is established by design because participants are assigned an exposure and followed forward in time to see whether the outcome develops (i.e. the exposure is known to precede the outcome in time)

2. Masking can minimize bias in how study procedures are conducted and/or how outcomes are ascertained or analyzed]

3. Randomization (with allocation concealment) can minimize bias due to confounding

4. Well-suited for studying rare exposures since the investigators assign the exposure conditions

4 limitations of controlled trials

1. Potential for loss to follow-up which could lead to selection bias

2. May not be well-suited to the study of rare outcomes and outcomes that take a long time to occur

3. Expensive, time-consuming, resource intensive, and require specific ethical considerations

4. May have limited generalizability to other populations or non-trial settings