44 Statistics and Patient Safety

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What does the null hypothesis state?

P value is less than 0.05

A difference exists between groups

Power of test is 0.8

No difference exists between groups (correct)

What does a Type I error (false positive) involve?

Accepting null hypothesis incorrectly

Setting P value at 0.01

Rejecting null hypothesis incorrectly (correct)

Increasing the power of a test

What does a Type II error (false negative) involve?

Rejecting null hypothesis incorrectly

Accepting null hypothesis incorrectly (correct)

Setting P value at 0.05

Increasing the power of a test

What does the power of a test indicate?

Probability of rejecting null hypothesis correctly Signup and view all the answers

What does a P value of 0.01 indicate?

1% chance of Type I error Signup and view all the answers

When does a test have a sufficiently powered indication?

Power ≥ 0.8 Signup and view all the answers

What is the purpose of the Time out before incision according to the JCAHO protocol?

Verifying patient, procedure, position site + side, and availability of implants or special requirements Signup and view all the answers

What is the main purpose of the GAP protection technique mentioned in the text?

Preventing loss of information and error due to gaps in care Signup and view all the answers

What is the definition of a Sentinel Event according to JCAHO?

An unexpected occurrence involving death or serious injury, or the risk thereof, resulting in root cause analysis Signup and view all the answers

What are the key elements of the JCAHO prevention protocol for wrong site/procedure/patient?

Preop verification, operative site and side marking, time out before incision, promoting culture of safety Signup and view all the answers

What are the risk factors for retained objects after surgery according to the JCAHO protocol?

Emergency procedure, unplanned change in procedure, obesity, towel used for closure Signup and view all the answers

What is the primary emphasis of the JCAHO protocol for prevention of wrong site/procedure/patient occurrences?

Promoting culture of safety Signup and view all the answers

Which statistical test compares means for 3 or more groups?

ANOVA Signup and view all the answers

What does sensitivity measure in a diagnostic test?

Likelihood a diseased person will test positive Signup and view all the answers

In a retrospective study, what type of bias is commonly observed?

Selection and recall bias Signup and view all the answers

Which statistical test analyzes the influence of 2 or more independent variables on a numerical outcome?

Multiple linear regression Signup and view all the answers

What does specificity measure in a diagnostic test?

Likelihood a person without disease will test negative Signup and view all the answers

What does incidence measure in epidemiology?

Number of new cases diagnosed over a certain time frame Signup and view all the answers

Which type of study compares those with a risk factor to those without and looks at disease rate?

Cohort study Signup and view all the answers

'Low SD' in statistical terms indicates that:

Values are close to the mean Signup and view all the answers

'Mode' in a set of data refers to:

7 Signup and view all the answers

'Prospective study' involves:

'Data is collected going forward for a patient population and analyzed at a future date' Signup and view all the answers

What is the most significant learning from conducting single-blinded RCT?

Patient and doctor are blinded to treatment Signup and view all the answers

What does Propensity score matched study do?

For a population with the same disease, matches a known treatment group and an artificially generated control group Signup and view all the answers

What is the formula for Positive Predictive Value (PPV)?

true-positives / (true-positives + false-positives) Signup and view all the answers

What does the Receiver Operating Curve (ROC) show?

Trade-off between sensitivity and specificity Signup and view all the answers

What is the probability of adverse outcome known as?

Absolute risk Signup and view all the answers

What does the term 'odds ratio' compare?

Odds of outcome in exposed group to odds of outcome in unexposed group Signup and view all the answers

What does a confidence interval indicate?

Range of values where there is a 95% probability the true value exists within it Signup and view all the answers

What does relative risk reduction measure?

Decrease in probability of outcome in treatment group compared to no treatment group Signup and view all the answers

What is lead time bias concerned with?

Earlier diagnosis making it look like patients are living longer Signup and view all the answers

How is detection bias (observer bias) solved?

(Solved with assessor blinding to patient’s status) Signup and view all the answers

What does National Surgical Quality Improvement Program (NSQIP) do?

Collects outcome data to measure and improve surgical quality; outcomes are reported as observed/expected ratios. Signup and view all the answers

How is absolute risk reduction calculated?

By subtracting the risk of an outcome in the treatment group from the risk in the control group. Signup and view all the answers

What does selection bias involve?

Selecting patients in a nonrandomized way. Signup and view all the answers