Henschke PJ, Spence JD, Cape RDT. Diuretics and the Institutional Elderly – a Case against Routine Potassium Prescribing. Journal of the American Geriatrics Society 1981;29(4):145-50.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/7204809
| Methods | Study design: Before-and-after case series
Number of groups: Two groups |
| Participants | Number of participants: 33 enrolled
· Intervention deprescribing group: 14 enrolled · Control group: 19 enrolled Age: 70 years (range 55 to 87 years) Sex: 0 female, 33 male Participants with dementia: No Inclusion criteria: · Receiving diuretics for cardiac failure under adequate control at the time of the study · Normal levels of hemoglobin · Biochemically normal renal function · Male · Resident at the participating residential aged care facilities Exclusion criteria: · Regularly taking laxatives, steroids or other drugs known to influence potassium status Other medicines: · Frusemide (dose range 20 – 80mg daily) n=10 · Hydrochlorothiazide (50 – 100mg daily) n=4 Diet: Dietary potassium intake was thus calculated at 100 milliequivalents per day Setting: Residential aged care Country: Canada |
| Interventions | Medicine: Potassium supplementation
Withdrawal schedule: Not stated Comparator: Oral potassium supplementation deprescribed in men receiving diuretic therapy for cardiac failure, compared to men without disease and not taking medicines likely to affect potassium levels |
| Outcomes | Potassium levels
Distributions of erythrocyte K values |
| Dates | Dates: Not stated
Follow-up duration: Three months |
| Funding sources | Not described |
| Notes | This study states that at that time, contemporary guidelines stated, “…in heart failure, potassium supplements are regarded as mandatory in elderly patients receiving diuretics…”
This study is, therefore, potentially less representative of the modern diuretic user who is not mandated to receive potassium. Note that although this study has a control group, the control group was only measured once, and was comprised of people without disease and not taking medicines known to alter potassium levels. |
Risk of bias table
| Bias | Authors’ judgment | Support for judgment |
| Random sequence generation (selection bias) | High risk | Not a randomized study design. |
| Allocation concealment (selection bias) | High risk | Allocation concealment not described nor claimed. |
| Blinding of participants and personnel (performance bias) | 5 out of 5 | The paper does not claim that it is blinded. |
| Blinding of outcome assessment (detection bias) | 5 out of 5 | The paper does not claim that it is blinded. |
| Incomplete outcome data (attrition bias) | 1 out of 5 | It is not indicated how many if any, participants dropped out of the study. It appears there is no missing data. |
| Selective reporting (reporting bias) | 5 out of 5 | There is no evidence of a pre-specified protocol or analysis plan, nor are the objectives sufficiently clear to ascertain if there was selective outcome reporting. However, the control group results are only reported for some outcomes.
Control group not reported except in graphs. |
| Confounding (non-randomized) | Unclear risk | Statistical analysis controlled for dietary potassium and other medicines that may alter serum potassium.
List of confounders considered was extensive. |
| Other bias | Unclear risk | Methods are insufficiently described to ascertain if there are other potential sources of bias. |
| Newcastle-Ottawa scale | ||
| Selection bias | Representativeness of the exposed cohort | Somewhat representative of the average contemporary male resident in long-term residential care prescribed diuretics (not necessary representative of a resident today). |
| Selection of the non-exposed cohort | No description of the derivation of the non-exposed cohort.
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| Ascertainment of exposure | Ascertainment of exposure by secure record. | |
| Demonstration that outcome of interest was not present at start of study | Demonstrated that outcome of interest was not present at start of study. | |
| Comparability bias | Comparability of cohorts on the basis of the design or analysis | The study controlled for deprescribing potassium supplementation adjunct to diuretic therapy. |
| Outcome bias | Assessment of outcome | Assessment of outcome by record linkage. |
| Was follow-up long enough for outcomes to occur | Follow-up may have been long enough for outcomes to occur. | |
| Adequacy of follow-up of cohorts | No statement on the adequacy of follow-up of cohorts. | |
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