| Course | NUR-7630 Biostatistics and Clinical Epidemiology |
|---|---|
| Module | Module 1 |
| Paper type | Measures of frequency and association |
| Length | About 1,042 words, 6 pages |
| Format | APA 7 student paper |
| School | Thomas Edison State University |
| Program | Doctor of Nursing Practice |
| Updated | October 2026 |
Free sample paper for NUR 7630 Module 1
8.6 Versus 6.2 Bleeds per 1,000 Person-Years: Working Rates, Risk Differences and a Number Needed to Harm From an Aspirin Trial in Older Adults
Student Name
Doctor of Nursing Practice, Thomas Edison State University
NUR-7630: Biostatistics and Clinical Epidemiology
Mentor Name
Month Day, Year
8.6 Versus 6.2 Bleeds per 1,000 Person-Years: Working Rates, Risk Differences and a Number Needed to Harm From an Aspirin Trial in Older Adults
A Standing Order Under Review
Our hospital's outpatient clinics have used a standing order since 2012 that prompts nurses to start low-dose aspirin for adults over 70 with no history of heart disease or stroke, unless the patient's clinician objects. The order was written when many guidelines still favored aspirin for primary prevention. As the hospital's quality director and a DNP student, I was asked to review whether it should continue. The answer depends on numbers, and on understanding what each number measures. This paper works through the measures from the largest trial in this population and explains what they mean for the order.
The Trial and Its Rates
McNeil et al. (2018) randomized 19,114 community-dwelling adults, most 70 or older, without cardiovascular disease, dementia or disability, to 100 milligrams of aspirin daily or placebo, in Australia and the United States. Over a median follow-up of 4.7 years, heart attacks, strokes and related events accrued at 10.7 for every thousand years of aspirin use and 11.3 for every thousand years on the dummy pill. Serious bleeding showed the opposite pattern: 8.6 episodes per thousand person-years on the drug against 6.2 on placebo.
These figures are incidence rates: new events divided by the total time that participants were followed and at risk. A rate of 8.6 per 1,000 person-years means that if 1,000 people were followed for one year, about 8.6 major bleeds would be expected, or equivalently that 100 people followed for 10 years would produce about the same number. Using person-time rather than people allows for the fact that participants were followed for different lengths of time.
Our own clinics can calculate the same measure. If 240 patients over 70 contributed a combined 1,000 years of follow-up last year and five had a major bleed, the clinic's rate would be 5 per 1,000 person-years, which can be set beside the trial's figures to see whether our population bleeds more or less often than the trial's volunteers.
Measures of Association
Two measures compare the groups. The rate ratio divides one rate by the other: for cardiovascular disease, 10.7 divided by 11.3 is 0.95, and for major bleeding, 8.6 divided by 6.2 is 1.39. The investigators' survival models gave hazard ratios almost identical to these simple ratios: 0.95 for cardiovascular events, interval 0.83 to 1.08, and 1.38 for serious bleeding, interval 1.18 to 1.62. A ratio below 1 means fewer events with aspirin; above 1, more.
Subtraction gives the second measure. For cardiovascular disease, 10.7 minus 11.3 is minus 0.6 events per 1,000 person-years, a tiny reduction. For major bleeding, 8.6 minus 6.2 is 2.4 additional bleeds per 1,000 person-years. A ratio describes how tightly aspirin and bleeding are linked; a difference counts the people hurt, and a rule that reaches thousands of patients has to be judged on the count.
| Measure | Cardiovascular disease | Major hemorrhage |
|---|---|---|
| Rate with aspirin per 1,000 person-years | 10.7 | 8.6 |
| Rate with placebo per 1,000 person-years | 11.3 | 6.2 |
| Rate ratio (simple) | 0.95 | 1.39 |
| Hazard ratio reported (95 percent CI) | 0.95 (0.83 to 1.08) | 1.38 (1.18 to 1.62) |
| Rate difference per 1,000 person-years | Minus 0.6 | Plus 2.4 |
Numbers Needed to Treat and to Harm
Laupacis et al. (1988) suggested turning an absolute risk difference upside down, its reciprocal, so that clinicians could see how many patients must be treated for one to gain. Cook and Sackett (1995) explained that it must always be tied to a time period and that, for harms, the same calculation gives a number needed to harm.
For major bleeding, the difference of 2.4 per 1,000 person-years equals 0.0024 per person-year. Its reciprocal is about 417 person-years: one extra major bleed for roughly every 417 years of aspirin use across a group. Over the trial's median of 4.7 years, that is about one additional major bleed for every 89 older adults started on aspirin.
For cardiovascular disease, no number needed to treat should be reported. The confidence interval for the hazard ratio, 0.83 to 1.08, includes 1, meaning the data are consistent with aspirin making no difference or even a small increase. Calculating a number needed to treat from a difference that may be zero would imply a benefit the trial did not show.
What the Numbers Mean for the Order
For every 89 healthy older adults started on aspirin under the standing order and taking it for about five years, one would be expected to have a major bleed that would not otherwise have occurred, with no clear reduction in heart attacks or strokes. Major bleeds in older adults include gastrointestinal hemorrhage and intracranial bleeding, which can be disabling or fatal. Our clinics enroll about 3,000 adults over 70 who would meet the order's criteria. Applying the trial's rate difference, about seven additional major bleeds a year could be expected across that group.
Limits of Applying the Trial
The trial enrolled relatively healthy volunteers who were free of disability and dementia and willing to take a daily pill for years; adherence in the final year was a little over 60 percent. Our clinic population is older and sicker on average, and both bleeding and cardiovascular risk may be higher. Individual patients with very high cardiovascular risk, or with other indications for aspirin, are not addressed by this analysis and should be assessed by their clinicians.
Recommendation
The standing order should be withdrawn. Clinicians may still prescribe aspirin for individual older adults when they judge the benefit to outweigh the bleeding risk, but the default should no longer be to start it. Patients already taking aspirin under the order should be flagged for review at their next visit, rather than stopped abruptly, since some may have developed other indications.
Conclusion
Working the trial's rates by hand shows the decision clearly. Aspirin produced a rate ratio near 1 and a rate difference near zero for cardiovascular disease, with a confidence interval that includes no effect, while major bleeding rose by 2.4 events per 1,000 person-years, one extra bleed for about every 89 people over five years. A standing order that exposes thousands of patients to that harm without clear benefit should not continue.
References
Cook, R. J., & Sackett, D. L. (1995). The number needed to treat: A clinically useful measure of treatment effect. BMJ, 310(6977), 452-454. https://doi.org/10.1136/bmj.310.6977.452
Laupacis, A., Sackett, D. L., & Roberts, R. S. (1988). An assessment of clinically useful measures of the consequences of treatment. New England Journal of Medicine, 318(26), 1728-1733. https://doi.org/10.1056/NEJM198806303182605
McNeil, J. J., Wolfe, R., Woods, R. L., Tonkin, A. M., Donnan, G. A., Nelson, M. R., Reid, C. M., Lockery, J. E., Kirpach, B., Storey, E., Shah, R. C., Williamson, J. D., Margolis, K. L., Ernst, M. E., Abhayaratna, W. P., Stocks, N., Fitzgerald, S. M., Orchard, S. G., Trevaks, R. E., ... Murray, A. M. (2018). Effect of aspirin on cardiovascular events and bleeding in the healthy elderly. New England Journal of Medicine, 379(16), 1509-1518. https://doi.org/10.1056/NEJMoa1805819
What the NUR 7630 Module 1 instructions ask for
Statistical measures applied to the distribution and determinants of disease open the NUR-7630 catalog description, and as TESU keeps the course syllabus private, this first module asks for exactly that: measures of frequency and association calculated from real data and used for a decision. Expect to compute rates or risks, ratios and differences, and often a number needed to treat or harm, showing every step, and then to explain what the results mean for a practice question. Some sections supply a data set or a two-by-two table instead of a published trial. Confirm whether hand calculation or software output is expected, and whether a table of results is required. Choose a study whose numbers bear on a decision in your own setting.
How the NUR 7630 Module 1 example is put together
The quality director introduces the standing aspirin order and why it is under review. The trial and its incidence rates are described, with the person-year unit explained in plain words. Ratios and differences for both outcomes are then worked out and set beside the published hazard ratios, and a short example shows how the clinics could compute their own bleeding rate. A section on numbers needed to treat and harm computes one extra bleed per 89 people over 4.7 years and explains why no benefit figure can be claimed. The implications for 3,000 clinic patients, the trial's limits and a recommendation to withdraw the order follow before the conclusion.
Reading the NUR 7630 Module 1 grading rubric
Epidemiology calculation papers are graded on correct calculations shown step by step, accurate interpretation of each measure and its units, and sound judgment about what the results support. Mentors look for ratios and differences both reported, numbers needed to treat or harm tied to a time period and confidence intervals checked before benefits are claimed. Applying results to a real population, with attention to how it differs from the trial's, shows practice relevance. The recommendation should follow from the numbers. APA references and a clear table of calculations complete the grade, and a worked example from the student's own setting shows that the measures are understood rather than copied.
NUR 7630 Module 1 help: mistakes that cost marks
Students often report only the relative measure, which can make small effects look large. Always give the absolute difference too. Another frequent error is computing a number needed to treat when the confidence interval includes no effect, which claims a benefit the data do not show. State the time period for every number needed to treat or harm. Explain units such as person-years in plain words. Check whether the trial population resembles yours before applying its results. Show each step so a reader can reproduce it. Send the study your NUR-7630 module assigns, and the desk will work its numbers in a first draft at no cost.
Write yours, or have the desk draft it
This paper is an original model document written by our desk, not a submitted student paper and not an official Thomas Edison State University document. Read it for the moves, then write your own to the instructions in your classroom. If you want one built to your exact prompt and rubric, the first custom sample is free and arrives in 24 to 48 hours.
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NUR 7630 Module 1 questions, answered
Where can I find a free NUR 7630 Module 1 sample paper?
The aspirin calculations are printed above in full, from incidence rates to a number needed to harm.
What is an incidence rate per 1,000 person-years?
The number of new events divided by the total time participants were followed, scaled to 1,000 years of follow-up, which allows for people being followed for different lengths of time.
What is the difference between a rate ratio and a rate difference?
The ratio divides one rate by the other and shows strength of association; the difference subtracts them and shows how many extra or fewer events occur.
How do you calculate a number needed to harm?
Take the reciprocal of the absolute increase in risk or rate, and state the time period. For 2.4 extra bleeds per 1,000 person-years, that is about one per 417 person-years.
Did aspirin prevent heart disease in healthy older adults?
In the ASPREE trial, the hazard ratio for cardiovascular disease was 0.95 with a confidence interval of 0.83 to 1.08, so no clear benefit was shown, while major bleeding increased.