UNIT 5 RESPONSE

POST EACH RESPONSE SEPARATELY

REPLY TO MY CLASSMATE DISCUSSION BELOW AND EXPLAIN WHY YOU AGREE (Lorraine)

MINIMUM OF 200 WORDS)

The measure of association I will be using as an example is relative risk. Relative risk is a

primary measure used to assess the strength of the relation between an exposure and an

outcome. An example is the relation of a risk factor or intervention to an outcome, typically a

disease or health condition. Relative risk is advantageous in case-control studies because these

studies are when researchers follow individuals over time to watch the development of an

outcome. Then, they compare based on exposure status.

These measures give tremendous value to public health decision-makers in many ways, such as

quantifying the impact of risk factors, identifying the cause, setting public health priorities, and

evaluating intervention effectiveness. These measures allow for assessing a specific risk factor

or exposure linked with a particular health outcome. Identifying causes can not be done

explicitly by measures of association; however, measures of association can provide evidence

of a relationship when put together with additional epidemiological criteria. Prioritization of

public health efforts is more efficient by decision-makers when measures of association are

utilized. When measures identify high relative risks associated with particular exposures, it will

highlight the need for rapid intervention. Lastly, measuring public health interventions can be

assessed by measurements of association. Comparing measures before and after an

intervention allows for a data-driven assessment of whether the intervention was effective.

REPLY TO MY CLASSMATE DISCUSSION BELOW AND EXPLAIN WHY YOU AGREE (Tiny)

MINIMUM OF 200 WORDS)

With any treatment there are risks. Absolute risk reduction enumerates those risks versus no

treatment at all. According to Barratt et al. (2004), these numbers are the most useful way of

presenting the risks in a quantifiable way (Barratt et al., 2004), Health decision makers use this

information regularly. It is a good process to implement if a facility wishes to avoid mal-practice

or a researcher desires publication. Studies on the effectiveness of public health interventions

present results in different ways. Knowing how to interpret those results not only helps the

researcher and the hospital administrator but the population as a whole. When the outcome is

defined as the presence or absence of an event, the outcome is often reported as the absolute

risk. Absolute risk is the percentage of people with the outcome within a group. In studies

evaluating the effectiveness of an intervention, the absolute risk is calculated for both the

intervention and control groups. Then, the two are compared.

Hypothetical Example

A study evaluates the effectiveness of an intervention to reduce brain damage among

premature babies. The researcher compares the number of babies with brain damage in those

exposed to the intervention and those not exposed.

300 premature babies are randomly allocated to intervention group

300 to control group with no intervention

90 babies in the control group experience brain damage.

Their absolute risk for brain damage is calculated by dividing 90/300= 0.30 or 30% of those in

control group. Baseline risk for brain damage for those in control group is 30% as the absolute

risk is equivalent to baseline risk for those not exposed to the intervention. The baseline risk for

brain damage in the intervention group is also around 30% but, after exposure to the

intervention, 54 premature babies acquire brain damage. Calculate absolute risk for brain

damage in the intervention group by dividing 54/300=0.18 or 18%. The intervention group has

an absolute risk for brain damage at 18% following intervention. Because the risk for brain

damage is lower following intervention. It is possible to calculate the absolute risk reduction.

This can be calculated by subtracting the absolute risk of those exposed to the intervention to

those not exposed. 30%-18%= absolute risk reduction of 12%. The intervention lowered the risk

for brain damage by 12%.

More Complete Data

According to Mayne et al. (2006), while the absolute risk reduction gives us an indication of the

impact of an intervention, more data can be uncovered (Mayne et al.,2006). The intervention

lowers the risk for brain damage by 12%. It is necessary to calculate the relative risk to find the

risk for brain damage remaining among those exposed to the intervention. The relative risk

takes into account the baseline risk for the outcome among those in the intervention group

compared to those in the control group. To calculate relative risk, divide absolute risk of

intervention group by absolute risk of control group. 18%/30%=0.60 this tells us that the risk for

brain damage among those in the intervention group is 60 % of the risk in the control group.

Now it is possible to calculate how much the risk for brain damage is reduced among those in

the intervention group. This refers to the relative risk reduction. It is calculated by subtracting

the Relative risk percentage from 100%. 100%-60%= 40%. So, the intervention reduces the

relative risk for brain damage by 40% among those exposed to the intervention. These stats are

important for different reasons.

A Lower Risk

Another study is conducted with the baseline risk for brain damage is 10%. This means the

absolute risk for brain damage in the control group is 10%. If the groups are randomly

allocated. We can assume the baseline risk in the intervention group is also about 10%. The

intervention has the same effect as in the first study. So, the relative risk reduction is 40%.

Therefore, following the intervention, the intervention group's risk for brain damage will be 40%

of 10% which means absolute risk in intervention group will be 6%. To calculate the absolute

risk reduction, we subtract absolute risk of 6% in the intervention group from the absolute risk

of 10% in the control group which is 4%. In this case, when the baseline risk for brain damage is

10% and the relative risk remains the same at 40% the absolute risk reduction for fracture is

only 4%.

Summary

In the first study the baseline risk for fracture is 30%. The absolute risk reduction is 12% and the

relative risk reduction is 40%. In the second study, even though the relative risk reduction

stayed the same at 40%, when the baseline risk drops to 10%, the absolute risk reduction

decreases to 4%. These two samples illustrate how baseline risk outcome influences absolute

risk reduction, even when the relative risk reduction remains the same. That's why it's

important to consider the baseline risk in your population prior to implementing an

intervention. If it's lower in the population than those in the study, the researcher can

anticipate the absolute risk reduction to be less than published. When baseline risk is higher

the opposite is true.

References

Barratt, A., Wyer, P. C., Hatala, R., McGinn, T., Dans, A. L., Keitz, S., & Moyer, V. (2004). Tips for

learners of evidence-

based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to

treat. Cmaj, 171(4), 353-358.

Mayne, T. J., Whalen, E., & Vu, A. (2006). Annualized was found better than absolute risk

reduction in the

calculation of number needed to treat in chronic conditions. Journal of clinical

epidemiology, 59(3), 217-223.