PU555 Unit 9 Measurement Plan Example

Down to the Equation, the Survey Item and the Cut Point: A Unit 9 Measurement Plan Giving Every Term in a Kidney Awareness Question an Operational Definition, Including the One That Changed in 2021

[Student Name]

Purdue University Global

PU555: Foundations of Public Health Research

Unit 9 Measurement Plan

[Instructor Name]

[Date]

The study is the course assignment's own; the equation, the survey items and the research cited are real.

Variable One: Kidney Function

1. Source value: serum creatinine, measured in the survey's mobile examination laboratory, in milligrams per deciliter, with the survey's own calibration adjustments applied as documented for each cycle.

2. Equation: the 2021 creatinine-based equation that removed the race coefficient (Inker et al., 2021).

3. Output: estimated filtration, continuous.

4. Analytic categories: 30 to 44 and 45 to 59, with a combined 30 to 59 band as the primary group, and below 30 reported separately rather than merged, since awareness rises steeply at that level.

5. Excluded: participants with no creatinine value, and participants reporting current dialysis, who are by definition aware.

Why the Equation Choice Is a Measurement Decision, Not a Formality

Removing the race coefficient lowers estimated filtration for participants previously assigned the higher coefficient, which moves some of them into the 30 to 59 band and others out of the band above it. The size of the group being studied therefore depends on which equation is used, and so does its composition. The plan uses the current equation and reports what the band would have contained under the older one, because the national task force that recommended the change framed it as a change in who is classified as having disease rather than only as an arithmetic adjustment (Delgado et al., 2022). Comparisons with awareness estimates published before 2021 are therefore approximate, and the plan says so in advance rather than in a limitations paragraph. Change the equation and the denominator changes, which means the awareness proportion changes without anybody's awareness changing at all.

Variable Two: Awareness

1. Item, quoted verbatim from the questionnaire: whether a doctor or other health professional ever told the participant they had weak or failing kidneys, excluding kidney stones, bladder infections or incontinence.

2. Coding: yes equals aware; no equals unaware; refused and do not know are retained as separate categories and reported, never recoded to no.

3. Primary outcome: the proportion answering yes among participants in the 30 to 59 band, weighted.

4. Known weakness: the item's wording sets a high bar, since weak or failing kidneys is stronger language than a clinician is likely to have used for stage 3 disease. Pooled work in this field shows published figures shifting a long way with wording of just this kind, so the item is printed in full beside every estimate the plan produces (Chu et al., 2021).

Variable Three: Usual Place of Care

1. Item: whether there is a place the participant usually goes when sick or needing advice about health.

2. Coding: yes, including clinic, doctor's office, health center or hospital outpatient department; no, including emergency room only, which is coded as no with the reason recorded.

3. Use: stratifying variable for the secondary comparison.

Covariates, With Their Definitions

1. Age in years, grouped as 20 through 44, then 45 through 64, then 65 upward.

2. Diabetes: either a yes to the ever-told item or a measured glycated hemoglobin of 6.5 percent or higher, with the definition stated because the two do not identify the same people.

3. Hypertension: measured mean of available readings at or above 130 over 80, or current antihypertensive use.

4. Albuminuria: urine albumin-to-creatinine ratio at or above 30 milligrams per gram, included because awareness varies with markers beyond filtration (Tuot et al., 2011).

5. Insurance and education as reported, used descriptively only.

Reliability and Validity, Stated Narrowly

Reliability of the laboratory value rests on the survey's documented quality control rather than on anything this study does. Reliability of the awareness item cannot be assessed within a cross-sectional file, since there is no repeat administration, and the plan does not claim otherwise. Validity of the awareness measure is the honest weak point: it measures recall of having been told, not what was said. The plan treats that as the construct of interest rather than as a flawed proxy, on the argument developed earlier in the course: when nothing of the telling survives in the patient's memory, the telling did not do its work.

Analysis Decisions That Belong in a Measurement Plan

1. Survey weights, strata and primary sampling units applied for every estimate; unweighted counts reported beside each proportion.

2. Cycles pooled, with a check that the awareness item's wording is identical across them before pooling.

3. Any estimate resting on fewer than 30 unweighted observations reported with its count and flagged as unstable rather than suppressed silently.

4. Missing covariates handled by complete-case analysis for the primary estimate, with a sensitivity check, since imputation of an outcome this study is trying to count would not be defensible.

What This Plan Deliberately Leaves Unmeasured

Three constructs the study wants and cannot measure here: what the clinician said, whether the patient understood it, and whether anything changed afterward. The first two are unavailable in any file, as an earlier seminar established, and the third requires follow-up this design does not have. They are the subject of the interview aim, and the measurement plan for the interviews is a coding framework rather than a set of variables, which is why it sits in the proposal rather than here.

References

Chu, C. D., Chen, M. H., McCulloch, C. E., Powe, N. R., Estrella, M. M., Shlipak, M. G., & Tuot, D. S. (2021). Patient awareness of CKD: A systematic review and meta-analysis of patient-oriented questions and study setting. Kidney Medicine, 3(4), 576-585. https://doi.org/10.1016/j.xkme.2021.03.014

Delgado, C., Baweja, M., Crews, D. C., Eneanya, N. D., Gadegbeku, C. A., Inker, L. A., Mendu, M. L., Miller, W. G., Moxey-Mims, M. M., Roberts, G. V., St Peter, W. L., Warfield, C., & Powe, N. R. (2022). A unifying approach for GFR estimation: Recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. American Journal of Kidney Diseases, 79(2), 268-288. https://doi.org/10.1053/j.ajkd.2021.08.003

Inker, L. A., Eneanya, N. D., Coresh, J., Tighiouart, H., Wang, D., Sang, Y., Crews, D. C., Doria, A., Estrella, M. M., Froissart, M., Grams, M. E., Greene, T., Grubb, A., Gudnason, V., Gutierrez, O. M., Kalil, R., Karger, A. B., Mauer, M., Navis, G., ... Levey, A. S. (2021). New creatinine- and cystatin C-based equations to estimate GFR without race. The New England Journal of Medicine, 385(19), 1737-1749. https://doi.org/10.1056/NEJMoa2102953

Tuot, D. S., Plantinga, L. C., Hsu, C. Y., Jordan, R., Burrows, N. R., Hedgeman, E., Yee, J., Saran, R., & Powe, N. R. (2011). Chronic kidney disease awareness among individuals with clinical markers of kidney dysfunction. Clinical Journal of the American Society of Nephrology, 6(8), 1838-1844. https://doi.org/10.2215/CJN.00730111