Retrospective Population-based Study on Epidemiology of Acute Mesenteric Ischemia in Estonia
Conditions: Acute Mesenteric Ischemia
Sponsor: Tartu University Hospital

 
 
 
 
 
 
 
Retrospective population-based study on epidemiology of acute mesenteric 
ischemia in Estonia 
 
 
Study Protocol (AMI version1.0) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
01.04.2021 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
Principal Investigator 
Karri Kase, MD 
Tartu University Hospital, Department of Surgery 
Estonia, Tartu City, Puusepa 8 
+3727318065 
karri.kase@kliinikum.ee 
Sub Investigators 
Peep Talving, MD, PhD 
The North Estonia Medical Centre, Clinical director, professor of surgery 
Estonia, Tallinn City, J. Sütiste 19 
+3726171525 
peep.talving@ut.ee  
 
Annika Reintam Blaser, MD, PhD 
University of Tartu, Department of Anaesthesiology and Intensive Care and Luzerner 
Kantonsspital, Department of Intensive Care Medicine  
Estonia, Tartu City, Puusepa 8 
+3725142281 
annika.reintam.blaser@ut.ee  
 
Kadri Tamme , MD, PhD 
Tartu University Hospital, Department of Anaesthesiology and Intensive Care 
Estonia, Tartu City, Puusepa 8 
+3727318414 
kadri.tamme@kliinikum.ee 
 
Marko Murruste, MD 
Tartu University Hospital, Department of Surgery 
Estonia, Tartu City, Puusepa 8 
+3727318065 
marko.murruste@kliinikum.ee 
 
Olga Kiss, MD 
Tartu University Hospital, Department of Anaesthesiology and Intensive Care 
Estonia, Tartu City, Puusepa 8 
+37253363610 
olga.kiss@kliinikum.ee  
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
 
Sergei Gordienko, MD 
Tartu University Hospital, Department of Anaesthesiology and Intensive Care 
Estonia, Tartu City, Puusepa 8 
+37258503358 
Sergei.gordienko@kliinikum.ee 
 
Martin Kivilo 
University of Tartu, Faculty of Medicine 
+3725176217 
martinkivilo@gmail.com  
 
Funding Sponsor 
Study is funded by Grant PRG 1255 (duration 2021-2025). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
Summary 
Title: Retrospective population-based study on epidemiology of acute mesenteric ischemia in 
Estonia 
Protocol number: AMI version1.0 
Study Design/Methodology: Retrospective population-based study 
Study duration: April 2021 until December 2022 
Study Center: primary study center: Tartu University Hospital, patients from all hospitals in 
Estonia included. 
Objectives: to describe epidemiologic features in adult patients with acute mesenteric ischemia 
Number of subjects: 500 
Eligibility criteria: all at least 18-year-old patients with acute mesenteric ischemia during years 
2016-2020. 
Study interventions: none 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
Background 
This study is a retrospective population-based study on epidemiology of acute mesenteric 
ischemia in Estonia.  
Acute mesenteric ischemia (AMI) is a potentially fatal vascular emergency with overall 
mortality of 60-80% (1). Acute mesenteric ischemia comprises a group of pathophysiologic 
processes that have a common end point – insufficient blood supply to the bowel leading to 
bowel ischemia and if blood supply is not restored fast, to transmural bowel necrosis 
(infarction): 
1. Occlusive mesenteric ischemia: 
a. Arterial thrombosis 
b. Arterial embolism 
c. Venous thrombosis 
2. Non-occlusive mesenteric ischemia (NOMI) 
There are no previous studies about the incidence of acute mesenteric ischemia in Estonia.  
Between 1970 and 1982 in Malmö (Sweden) autopsies were conducted on as many as 87% of 
the deceased in the population of approximately 250 000 inhabitants. They found that the 
annual incidence of AMI was 12 per 100 000 inhabitants. (2). There has not been comparable 
study to Malmö cohort.  
Between 2009 and 2013 Kärkkäinen JM et al studied patients with acute abdomen and found 
that the incidence rate of AMI was 7,3/100 000/year. (3).  
Considering that population is aging and AMI primarily affects elderly then potentially 
incidence of AMI should increase. However, abovementioned studies suggest that it may rather 
decrease. Reasons for that could be better control and treatment of comorbidities. For example 
such development has been shown for cardiovascular events. (4)(5).  
There are no large studies about the risk factors of AMI, but the main etiologic factor is 
atherosclerosis. (6).  
Beaulieu and colleagues found a total of 23744 hospital admissions for AMI registered in the 
Nationwide Inpatient Sample database from 2005 to 2009. Only 3% received an attempt of 
open or endovascular revascularization, while 17% were treated with bowel resection alone, 
and 80% received no intervention whatsoever. (7).  
Meanwhile studies have shown that correct diagnosis in right time and subsequent adequate 
treatment could potentially save more than half of AMI patients. (8).  
According to this acute mesenteric ischemia needs definitely greater interest and continuing 
studies to improve diagnostics and treatment. 
 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
Study objectives 
Primary objective: 
To identify the incidence of AMI in adult hospitalized patients in Estonia during 2016-2020. 
Secondary objectives: 
To describe the phenotype of AMI. 
To describe treatment modalities and outcome of AMI. 
Results obtained from this study will be used for designing a prospective multi-center study 
about AMI.  
 
Study design and methods 
Sample size 
1. Previous studies (1-3) have found that incidence of AMI could be 6-12/100 000/year.  
2. We do not have exact primary data about AMI in Estonia and that is why we could not 
calculate precise sample size. We assume that 500 patients with AMI is sufficient to 
describe also different subgroups (see above).  
3. In view of prior we plan to analyze data from 5 years and will collect the most recent 
data (years 2016-2020). 
Study data 
To identify the patients of interest, we ask Estonian Health Insurance Fund to extract data for 
all cases where diagnostic and procedure codes covering acute mesenteric ischemia during 
years 2016-2020 have been documented. 
Diagnostic codes (ICD-10) and procedure codes (NOMESCO) that cover acute mesenteric 
ischemia: 
1. ICD-10: I74.0, I74.1, I74.8, I74.9, I81, K55.0, K55.1, K55.8, K55.9  
2. NOMESCO: PCE30, PCF30, PCG30, PCH30, PCJ30, PCK30, PCN30, PCP30, 
PCQ30, PCR30, PCT30 
We ask for the following information for each patient: 
1. Number of case  
2. Personal identification code 
3. When and where (name of the hospital) this patient was hospitalized with respective 
diagnostic code 
From these patients we will identify those who truly have AMI, based on the following 
criteria: 
 Occlusive acute mesenteric ischemia:  

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
a. appropriate clinical presentation of life-threatening acute intestinal ischemia 
with  
b. thrombosis or embolism of the mesenteric arteries or thrombosis of the 
mesenteric veins and  
c. either presence of pathological intestinal findings on a computer tomography 
(CT) scan (bowel wall thickening, abnormal bowel wall enhancement, or 
luminal 
dilatation) 
or 
bowel 
necrosis 
identified 
at 
laparoscopy/laparotomy/autopsy.  
 Nonocclusive mesenteric ischemia (NOMI): 
a. acute intestinal ischemia based on clinical presentation pattern and  
b. pathological intestinal findings on a CT scan or bowel necrosis on 
laparoscopy/laparotomy or autopsy 
c. without significant (<70 %) obstruction of the superior or inferior mesenteric 
artery.  
The primary data screening will be performed by the principal investigator using Estonian 
Health Information System. 
For patients who likely had AMI, data collection from medical case charts will be initiated. 
Data collection in different hospitals will be organized by the principal investigator. 
Also, we ask from Estonian Health Insurance Fund the total number of adult patients admitted 
to different Estonian hospitals for years 2016-2020 to calculate the incidence of AMI in adult 
hospitalized patients. 
From Estonian Causes of Death Registry we ask data about all cases of death of the patients 
with acute mesenteric ischemia in the final database and their death certificate diagnoses to 
identify mortality outcome. 
Database 
The exact data that will be collected are shown in Annex 1. 
All data will be entered in a Microsoft Excel database. The data will be pseudonymised -  each 
patient will be assigned a unique study-ID. The key, to identify patients will be stored separately 
from the database on a secure server of Tartu University Hospital in a password protected file 
and can be accessed only by the principal investigator. Database will be stored separately from 
the key on a server of Tartu University Hospital in a password protected file and can be accessed 
by study investigators.  
Statistical analysis 
The study population will be described using common statistics (minimum, maximum, mean 
with standard deviation or median with interquartile range, standard error). The software 
package Statistica version 13.3 (TIBCO Software, California, USA) will be used for statistical 
calculations. 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
 
Ethical Considerations 
 
Our study is retrospective and descriptive, there is no intervention and researchers do not 
intercede.  
Data protection 
In the study it is necessary to use personalized medical data, because queries from different 
registries are made using the personal identification code. The study aims cannot be fulfilled 
using anonymous data.  
Data will be processed without the data subject's consent. Asking for informed consent is not 
possible as AMI has high mortality and most of these patients are not available for asking 
informed consent. Omitting these patients would seriously decrease the quality of the study.  
Measures to safeguard the fundamental rights and the interests of the data subject: 
 From Estonian Health Insurance Fund and Estonian Causes of Death Registry all 
data will be sent in encrypted form and will be decrypted by the principal 
investigator. 
 Only pseudonymised data will be entered in the database. Each patient will be 
assigned a unique study-ID. The key, to identify patients will be stored separately 
from the database on a secure server of Tartu University Hospital in a password 
protected file and can be accessed only by the principal investigator. Database will 
be stored separately from the key on a server of Tartu University Hospital in a 
password protected file and can be accessed only by study investigators. 
 Medical case files will not be sent via Internet or post. The principal investigator 
will go to the hospitals and enter the data to the database there. 
 Only pseudonymized data will be used for data analysis and publication of results. 
 The key to identify patients will be destroyed 3 years after the end of the study 
(31.12.2025) 
 After the key is destroyed the database becomes anonymous. The anonymous 
database will be kept for 15 years. 
Data controller: University of Tartu. 
The collected data are going to be used only for publishing scientific articles about acute 
mesenteric ischemia. No information that allows identification of the study subjects will be 
published.  
Data will not be used for financial purposes. 
The Study has been approved by Research Ethics Committee of the University of Tartu (337/T-
20). Approval of Estonian Committee of Bioethics and Human Research will be obtained. 
 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
01.04.2021 
 
References 
 
1. Oldenburg WA et al. Acute mesenteric ischemia: A Clinical Review. Arch Intern 
Med. 2004;164:1054-1062 
2. Acosta S. Epidemiology of mesenteric vascular disease: clinical implications. Semin 
Vasc Surg 2010;23(1):4-8 
3. Kärkkäinen JM et al. Acute mesenteric ischemia is a more common cause than 
expected of acute abdomen in the elderly. J Gastrointest Surg 2015;19(8):1407-14 
4. Salomaa V et al. Aging of the population may not lead to an increase in the numbers 
of acute coronary events: a community surveillance study and modelled forecast of the 
future. Heart 2013;99(13):954-9 
5. Borodulin K et al. Forty-year trends in cardiovascular risk factors in Finland. Eur J 
Public Health 2015;25(3):539-46 
6. Lehtimäki TT et al. Detecting acute mesenteric ischemia in CT of the acute abdomen 
is dependent on clinical suspicion: review of 95 consecutive patients. Eur J Radiol 
2015;84(12):2444-53 
7. Beaulieu RJ et al. Comparison of open and endovascular treatment of acute mesenteric 
ishemia. J Vasc Surg 2014;59(1):159-64 
8. Kärkkäinen JM et al. Endovascular therapy as a primary revascularization modality in 
acute mesenteric ischemia. Cardiovasc Interv Radiol 2015;38(5):1119-29 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
AMI Version 1.0 
 
 
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Annex 1 
Data that will be collected  
1. General 
a. Gender (M/F) 
b. Age (y) 
c. Hospital 
2. Health condition  
a. Disability (no need of assitance/needs/No information(NI)) 
b. Consciousness (Adequate/Disturbed/No contact/NI) 
c. Weight (kg/NI) 
d. Height (cm/NI) 
e. BMI (kg/m2) 
f. Smoking (yes/no/NI) 
3. Diagnoses 
a. Atrial Fibrillation (yes/no/NI) 
b. Atherosclerosis (yes/no/NI)  
c. Hypertonic disease (yes/no/NI)  
d. Hypercholesterolemia (yes/no/NI)  
e. Previous myocardial infarction (yes/no/NI)  
f. Previous thromboembolic events (yes/no/NI)  
g. Artificial heart valve (yes/no/NI)  
4. Diagnoses II 
a. Important main or accompanying pathology  
5. Mediactions 
a. Anticoagulant drugs (yes/no/NI)  
b. Antiplatelet drugs (yes/no/NI)  
c. Statins (yes/no/NI)  
6. Emergency Department 
a. Arrival to hospital (by self, ambulance) 
b. Occured during hospital treatment (then yes here, and previous is left empty) 
c. Arrival to hospital since the beginning of symptoms (hours (h)/unclear) 
d. Time from admition to hospital since CT-scan (h) 
e. Time from beginning of symptoms to diagnoosis (h) 
f. Time from arrival to hospital since diagnoosis (h) 
7. Laboratory tests 
a. Lactate (mmol/l/NI) 
b. WBC (x 10E9/L/NI) 
c. Creatinine (mcmol/l/NI 
d. eGFR (mL/min/1,73m27/NI) 
e. BE (mmol/l/NI) 
f. ASAT (U/L/NI) 
g. Amylase (U/L/NI) 
h. D-dimers (mg/L/NI) 
i. Troponin T (ng/L/NI) 
 
 

Retrospective population-based study on epidemiology of acute mesenteric ischemia in Estonia 
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8. Radiography 
a. What was the first radiographic study (x-ray, US, CT/NI) 
b. Was there a CT-scan made (yes/no)  
c. Phase of enhancement in CT-scan (no contrast media, portal venous, arterial, 
delayed phase) 
d. Radiologist diagnosed AMI (yes/no) 
e. Time between CT-scan and the response by radioloogist (min)  
9. Type of AMI 
a. Arterial embolism (a. mes. sup. – aortic ostium, until  separation of a. colica 
media, peripheral) 
b. arterial thrombosis (a. mes. sup. – aortic ostium, until  separation of a. colica 
media, peripheral) 
c. arterial non specified (a. mes. sup. – aortic ostium, until  separation of a. colica 
media, peripheral) 
d. Venous  
e. NOMI 
f. Other location (truncus coealiacus or a. mes. inf.) 
g. Unclear 
10. Treatment  
a. Time from beginning of symptoms to treatment (h) 
b. Time from diagnosis to treatment (h)  
c. Surcigal tactics (diagnostic laparoscopy, diagnostic laparotomy, therapeutic 
laparotomy, second-look tactics) 
d. Vascular tactics (embolectomy, thrombectomy, endarterectomy, 
aortomesenteric shunt) 
e. Gastrointestinal tactics (no need, resection with primary anastomosis, resection 
with stoma formation, resection without anastomosis and second look) 
f. Intestinal resection (cm/NI) 
g. Resection of colon (no need, right hemicolectomy, subtotal colectomy)  
h. Endovascular treatment  (aspiration of thrombus/embolism, ballondilatation, 
stent placement, thrombolysis, combined) 
i. Conservative treatement 
j. End-of-life care 
11. Hospital treatment 
a. Duration 
b. End (discharged, death) 
c. 30 day survival (alive/dead) 
d. 90 day survival (alive/dead) 
e. 180 day survival (alive/dead) 
f. 360 day survival (alive/dead)