Time to Excretion of Contrast, a Maastricht Prospective Observational Study

Study Overview
=================
Brief Summary
-----------------
Risk of contrast-induced kidney injury is expected to be strongly correlated with exposure time. Studies on the excretion of iodinated contrast material are few and have mostly been carried out in patients with normal renal function. Although case wise reports of persistent renograms have been published, it is not known how long contrast is retained before excretion in patients with eGFR <30 mL/min/1.73m2, nor which of these patients are most susceptible to contrast retention. The current observational study aims to compare contrast elimination time and % contrast excretion in patients with eGFR <30 mL/min/1.73m2, to matched patients (for age, sex and contrast procedure type) with eGFR 30-59 and eGFR >=60 mL/min/1.73m2.

Detailed Description
-----------------
The primary aim of the current study is to determine contrast elimination time and % in three groups of patients, (with severely reduced, moderate, and mildly reduced to normal renal function). Secondary aims are to explore whether specific situations/characteristics result in higher probability of delayed elimination of contrast, and whether there is a link between elimination time and adverse post-contrast outcomes (post-contrast incidences of acute kidney injury; post-contrast changes in eGFR within 5 days from baseline; 1-month post-contrast change in eGFR; 1-month post-contrast incidences of eGFR decline >=5 mL/min/1.73m2; 1-month dialysis and mortality).

Official Title
-----------------
Time to Excretion of Contrast, a Maastricht Prospective Observational Study

Conditions
-----------------
Renal Insufficiency, Acute Kidney Injury, Contrast-induced Nephropathy

Intervention / Treatment
-----------------
* Diagnostic Test: Contrast concentration in urine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: - eGFR <30 mL/min/1.73m2 in absence of dialysis referred for an elective procedure with intravascular administration of iodinated contrast material at Maastricht UMC+ For each included patient with eGFR <30 mL/min/1.73m2, two matched patients will be included: 1. eGFR 30-59 mL/min/1.73m2 referred for an elective procedure with intravascular administration of iodinated contrast material at Maastricht UMC+ with age, sex and contrast procedure type matching the age, sex and contrast procedure type of an eGFR <30 mL/min/1.73m2 participant. 2. eGFR >=60 mL/min/1.73m2 referred for an elective procedure with intravascular administration of iodinated contrast material at Maastricht UMC+ with age, sex and contrast procedure type matching the age, sex and contrast procedure type of an eGFR <30 mL/min/1.73m2 participant. Exclusion Criteria: age <18 years dialysis or pre-dialysis intravascular contrast administration having occurred <30 days before the first baseline sample emergency or intensive care status.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| eGFR <30 mL/min/1.73m2<br>Patients with eGFR <30 mL/min/1.73m2 in absence of dialysis referred for an elective procedure with intravascular administration of iodinated contrast material at Maastricht UMC+. | Diagnostic Test: Contrast concentration in urine<br>* Iodinated contrast content of urine samples, collected post-contrast over a period of 5 days at all times of natural excretion within that period, will be assayed. Serum creatinine will be measured daily before (day 0) and during 5 days post-contrast, and again at 1 month post-contrast.<br>|
| eGFR 30-59 mL/min/1.73m2<br>For each included patient with eGFR <30 mL/min/1.73m2, two patients matched for age, sex and contrast procedure type will be included: one with eGFR 30-59 mL/min/1.73m2 and one with eGFR >=60 mL/min/1.73m2. | Diagnostic Test: Contrast concentration in urine<br>* Iodinated contrast content of urine samples, collected post-contrast over a period of 5 days at all times of natural excretion within that period, will be assayed. Serum creatinine will be measured daily before (day 0) and during 5 days post-contrast, and again at 1 month post-contrast.<br>|
| eGFR >=60 mL/min/1.73m2<br>For each included patient with eGFR <30 mL/min/1.73m2, two patients matched for age, sex and contrast procedure type will be included: one with eGFR 30-59 mL/min/1.73m2 and one with eGFR >=60 mL/min/1.73m2. | Diagnostic Test: Contrast concentration in urine<br>* Iodinated contrast content of urine samples, collected post-contrast over a period of 5 days at all times of natural excretion within that period, will be assayed. Serum creatinine will be measured daily before (day 0) and during 5 days post-contrast, and again at 1 month post-contrast.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| time to contrast-free urine. | time to the first contrast-free urine sample from the time of intravascular iodinated contrast administration. Time to contrast-free urine will be compared between three groups of patients (with eGFR <30 mL/min/1.73m2, eGFR 30-59 mL/min/1.73m2, and eGFR >=60 mL/min/1.73m2). | 5 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| % contrast elimination. | percentage of total contrast administered excreted in urine within 5 days. Percentage contrast elimination will be compared between three groups of patients (with eGFR <30 mL/min/1.73m2, eGFR 30-59 mL/min/1.73m2, and eGFR >=60 mL/min/1.73m2). | 5 days | 
| contrast elimination versus adverse post-contrast outcomes. | The underlying hypothesis is that delayed elimination increases contrast toxicity which increases adverse event risk. This will be explored by comparing percentages with post-contrast adverse events (acute kidney injury; changes in eGFR; eGFR decline ≥5mL/min/1.73m2; dialysis; mortality; up to 1-month) in groups with and without delayed elimination, stratified by eGFR (<30, 30-59, ≥60). Relevant patient and procedural characteristics will also be compared to identify potential predictors of delayed elimination. Contrast elimination times are unknown, therefore 'delayed' is defined as time to contrast-free urine exceeding patient group median value. In clinical practice, normal contrast elimination is assumed to be ≥24h. Therefore, 1. Normal (≤24h); 2. Delayed (24-48h); 3. Severely delayed (>48h) elimination subgroups will also be compared. Subgroup cut-off values may be added at a later stage (e.g., in the event of many or no patients with elimination >48h). | 1 month | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
intravascular iodinated contrast, contrast-induced acute kidney injury, post-contrast acute kidney injury, iodinated contrast elimination time, contrast retention, delayed contrast elimination