PPGH Flashcards
The incubation period (from exposure to onset of symptoms) for Hepatitis B is typically?
40-160 days
What is the R0 (reproduction number)?
How many people one infected person will infect.
Incubation period for measles?
10-12 days
What is the R0 for measles?
12-18
A 3-year child has confirmed meningococcal meningitis. Which of the below contacts should receive chemoprophylaxis with Ciprofloxacin?
Doctors/Nurses who saw child in hospital
B.Grandparents who visited child last week for lunch
C.Children at the same day nursery
D.5-year-old Sibling
E.The next door neighbours
5 year old sibling
Only chemoprophylaxis is needed for household members.
Fatal complication of “STEC” - Shiga toxin producing E.coli
Haemolytic uraemic syndrome
Explain the presence of HBsAg on a blood test result:
Surface antigen(HBsAg) – active infection
HBeAg
E antigen(HBeAg)– a marker of viral replication and implies high infectivity
HBcAb
Core antibodies(HBcAb) – implies past or current infection
HBsAb
Surface antibody(HBsAb) – implies vaccination or past or current infection
HBV DNA
Hepatitis B virus DNA(HBV DNA) – this is a direct count of the viral load
How should hepatitis B be screened for?
When screening for hepatitis B, testHBcAb(for previous infection) andHBsAg(for active infection). If these are positive do further testing forHBeAgandviral load(HBV DNA).
What is Coomb’s test?
Antiglobulin testing, also known as the Coombs test, is an immunology laboratory procedure used to detect the presence of antibodies against circulating red blood cells (RBCs) in the body, which then induce hemolysis.
What medication is first line to treat Hep B?
Pegylated interferon-alpha
Summarise how you would explain what hep B is to a patient.
Hepatitis B is a double-stranded DNA hepadnavirus and is spread through exposure to infected blood or body fluids, including vertical transmission from mother to child. The incubation period is 6-20 weeks.
The features of hepatitis B include fever, jaundice and elevated liver transaminases.
Most common cause of haemolytic uraemic syndrome
Shiga toxin-producing Escherichia coli (STEC) 0157:H7
What triad does haemolytic uraemic syndrome present with?
- Acute kidney injury
- Microangiopathic haemolytic anaemia
- Thrombocytopenia
Observational research that analyzes data collected from a population at a specific point in time, in order to draw conclusions about the prevalence of a particular condition or characteristic within that population.
Cross Sectional Study
Observational research that analyzes data collected from a group of people who share a common characteristic or experience at some point in the past. Researchers follow up with these individuals to track the development of a particular outcome or condition over time. This study design evaluates the association between exposure to a risk factor and the development of an outcome or condition, while accounting for other potential confounding factors.
Retrospective cohort study
Starts with people free of the disease at baseline. Measure incidence. Establishes temporality by looking at the temporal relationship between two things.
Prospective cohort study
A prospective cohort study is an observational research design in which a group of individuals who do not have a particular condition or outcome of interest at the beginning of the study (baseline) is followed over time to assess the incidence of the condition or outcome. Researchers can then evaluate the association between exposure to a risk factor and the development of the condition or outcome, while accounting for potential confounding factors. The incidence rate ratio or relative risk is commonly used to measure the association between the risk factor and the outcome in a prospective cohort study. Prospective cohort studies are considered to be a strong study design for evaluating the causal relationship between a risk factor and an outcome, but they can be expensive, time-consuming, and subject to selection bias and loss to follow-up.
Observational study where researchers compare individuals with a particular condition or outcome (cases) to individuals without the same condition or outcome (controls). The goal of the study is to determine if there is a significant difference in the exposure to a particular risk factor between the cases and controls. The odds ratio is commonly used to measure the association between the risk factor and the outcome.
Case control study
Active surveillance vs passive surveillance:
Passive surveillance in public health involves healthcare providers or laboratories reporting cases of a disease or condition to public health officials. This is mandatory for certain diseases or conditions and relies on timely and accurate reporting. Active surveillance, on the other hand, involves public health officials searching for cases of a disease or condition in the community on a regular and systematic basis.
What is the difference between absolute and relative measures of association?
Absolute measures of association, such as risk difference or attributable risk, quantify the difference in risk between two groups. Relative measures of association, such as relative risk or odds ratio, quantify the strength of association between an exposure and an outcome.
While absolute measures of association are useful for understanding the impact of an exposure on the population, relative measures of association are more useful for understanding the strength of the association between an exposure and an outcome, as well as for comparing the strength of association across different exposures or outcomes.
Sentinel surveillance
Sentinel surveillance is a public health monitoring system that detects disease outbreaks or changes in disease patterns by monitoring a specific population or group of individuals. Through a representative sample of individuals or locations, sentinel surveillance provides early warning of disease outbreaks and helps identify changes in disease frequency or severity. This information informs public health interventions and policy decisions.
Syndromic surveillance
Syndromic surveillance is a public health system that uses real-time data to detect early signs of disease outbreaks or changes in disease patterns by monitoring non-specific symptoms or syndromes that are associated with a particular disease, such as fever or rash. This allows public health officials to detect outbreaks earlier and respond faster to prevent further transmission.
Cluster randomised control trial
A cluster randomized trial randomly assigns groups of people to receive a particular intervention or treatment, instead of individuals. This is used when it’s not practical to randomize each person separately, like in public health interventions or educational programs. The goal is to evaluate the intervention’s effectiveness at the group level while accounting for clustering effects within the groups.
How does PPV and NPV change with prevalence?
PPV increased with increased prevalence.
NPV decreases with increased prevalence.
What is the Stacey matrix used for?
Medical complexity and uncertainty
What is primary prevention?
Primary Prevention: This type of prevention focuses on preventing the onset of a disease or injury.
Examples of primary prevention include vaccination, exercise, and wearing safety gear.
What is secondary prevention?
Secondary Prevention: This type of prevention is focused on detecting a disease or injury early and taking action to prevent it from getting worse. It involves screening or testing to identify a condition before it becomes more severe.
Examples of secondary prevention include cancer screenings, regular check-ups, and monitoring blood pressure.
What is tertiary prevention?
Tertiary Prevention: This type of prevention is focused on reducing the impact of an existing disease or injury. It involves taking actions to slow or stop the progression of a condition and to prevent complications.
Examples of tertiary prevention include rehabilitation, medication, and lifestyle changes.
What is the equation for calculating relative risk?
Relative Risk = (Incidence rate in exposed group) / (Incidence rate in unexposed group)
(Where the incidence rate is the number of people who experience the outcome divided by the total person-time at risk in the group).
How do you calculate absolute risk?
Absolute Risk = (Number of people who experience the outcome) / (Total number of people in the population)
How do you calculate the NNT?
(number needed to treat)
NNT = 1 / (Rc - Re)
Rc = Event rate in control group (placebo).
Re = Event rate in experimental group.
or
1/ Absolute risk reduction
What is the forest plot used for?
A forest plot is a graphical representation of the results of a meta-analysis, which is a statistical technique used to combine the results of multiple studies.
How to interpret forest plots?
A forest plot is a graphical representation of the results of a meta-analysis, which is a statistical technique used to combine the results of multiple studies. The plot displays the effect estimates and confidence intervals for each study included in the meta-analysis, as well as the overall effect estimate and confidence interval. The width of each box represents the weight of the study, while the diamond represents the overall effect estimate. If the confidence interval for a study crosses the line of no effect (often represented by a vertical line at 1), then the study is not statistically significant.
If the confidence interval for a study does not cross the line of no effect, then the study is statistically significant.
The size of the box for each study is proportional to the inverse variance of the effect estimate, which is a measure of the precision of the estimate.
What is the inverse care law?
The Inverse care law is the idea that medical care tends to be more available to populations that need it less.
What is a meta analysis?
A meta-analysis is a type of research study that combines the results from multiple individual studies to obtain a more comprehensive understanding of the research question. By pooling data from multiple studies, meta-analyses can often provide more precise estimates of the effect of an intervention or exposure, as well as identify potential sources of variation or inconsistency across studies.
What study is used to assess prevalence of disease?
Cross sectional study
What study looks at the outcome and then back at the exposure?
Case control study
What measure can be calculated from a case control study?
Odds ratio
What study starts with people free of disease and measures incidence over time?
Prospective cohort study
What is the main advantage of a cohort study?
It allows you to establish a temporal relationship between exposure and outcome.
How to calculate relative risk?
Relative risk = Risk in exposed / Risk in unexposed
Relative measures of effect are independent of baseline risk.
Relative measures of effect are independent of baseline risk.
Felty’s syndrome
Rheumatoid arthritis, splenomegaly, low WCC
How to calculate relative risk reduction?
Relative Risk Reduction = 1 - Relative Risk
Note: Relative Risk = (Incidence rate in exposed group) / (Incidence rate in unexposed group)
What study design can establish causality?
RCT
