Establishment of the SingHealth Diabetes Registry

Figures & data

Table 1 Criteria Used for Case Ascertainment

Criteria	Details	Healthcare Setting
Diagnosis codes	At least one primary or secondary ICD-9-CM^a diagnosis codes of 250.xx, 362.0x, 357.2 or 366.41	Inpatient (pre-2012)
	At least one primary or secondary ICD-10-CM^a diagnosis codes starting with E10, E11, E13 or E14	Inpatient (2012 onwards)
	At least one SNOMED-CT diagnosis code related to diabetes mellitus. (List of codes in Supplementary Table 1)	Outpatient
	At least one SingHealth Polyclinic (SHP) Working Diagnosis Codes for diabetes mellitus. (List of codes in Supplementary Table 2)	Outpatient
Prescription records	At least one glucose lowering drug (GLD) prescribed.	Inpatient and outpatient
	GLDs include biguanides, sulphonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 receptor agonists, and insulin preparations.
Laboratory test records	Any one of the following:	Inpatient and outpatient
	- Positive oral glucose tolerance test (OGTT)
	> fasting plasma glucose >/= 7.0 mmol/L and/or
	> plasma glucose >/= 11.1 mmol/L at 2 hours
	- HbA1c >/= 7.0%

Note: ^aICD-10-CM replaced the ICD-9-CM in 2012.

Table 2 Details of Casemix Variables

Category	Items
Demographics and lifestyle factors	Gender
	Date of birth (used to calculate age)
	Ethnicity (Chinese, Indian, Malay, Others)
	Nationality
	Postal code, housing type (derived from postal code)
	Death date
	Smoking status
Diagnosis Profile	Diabetes type
	Year of diagnosis
	Comorbidities (Hypertension, hypercholesterolemia, established cardiovascular disease^a, ischemic heart disease, myocardial infarction, unstable angina, coronary artery bypass graft, cardiac catheterization, percutaneous coronary intervention, peripheral artery disease, cerebrovascular disease, ischemic stroke, hemorrhagic stroke, transient ischemic attack, angina pectoris, heart failure, atrial fibrillation)
Treatment factors	Glucose lowering drugs (GLDs)
	Anti-lipids
	Anti-hypertensives
	Anti-platelet
Anthropometric	Height, weight, body mass index
	Systolic blood pressure, diastolic blood pressure
	Heart rate

Table 3 Details of Outcome Variables

Category	Items
Laboratory results	Glycemic indices: HbA1c, Glucose
	Lipid panel (Total Cholesterol, HDL-cholesterol, LDL-cholesterol, Triglycerides)
	Liver indices (Serum ALT^a, AST^b, GGT^c, albumin)
	Renal indices (Serum urea, creatinine, potassium)
	Urinalysis (Urine microalbumin/creatinine ratio, urine protein/creatinine ratio)
	Hematological indices (Hemoglobin, white blood cell count, platelet count)
	Serum creatine kinase
	Serum NT-proBNP
Clinical episodes	Hospital admissions, emergency department visits
	Outpatient visits
Surgical procedures	Bariatric surgeries
	Lower extremity amputation
	Lower limb bypass and revascularization
	Coronary artery bypass grafting
	Percutaneous coronary interventions
Vaccinations	Influenza vaccination

Figure 1 Venn diagram of individuals identified by ascertainment criteria.

Table 4 Total Counts of Individuals

Healthcare Site Acronym	Description	Individuals Contributed, n (%)
SHP	SingHealth Polyclinics, comprising 8 primary healthcare clinics	116,576 (56.0)
SGH	Singapore General Hospital, tertiary referral hospital	25,317 (12.2)
CGH	Changi General Hospital, tertiary referral hospital	14,501 (7.0)
SKH	Sengkang General Hospital, tertiary referral hospital	3611 (1.7)
KKH	KK Women’s and Children’s Hospital, national pediatric and women’s hospital	2260 (1.1)
NHCS	National Heart Center Singapore, national cardiac referral center	7672 (3.7)
NCCS	National Cancer Center Singapore, national cancer referral center	640 (0.3)
SNEC	Singapore National Eye Center, national ophthalmology referral center	72 (0)
External	None of the above sites	37,453 (18.0)

Table 5 Summary Statistics of All Individuals

Variable		Overall Cohort (N=208,102)	Cohort Excluding Patients Managed at External Site (n=170,649)
Mean age, years (SD)		65.8 (13.7)	65.9 (13.5)
Sex, n (%)	Male	106,657 (51.3)	88,154 (51.7)
Ethnicity, n (%)	Chinese	144,482 (69.4)	118,274 (69.3)
	Malay	31,482 (15.1)	26,265 (15.4)
	Indian	22,930 (11.0)	18,442 (10.8)
	Others	9208 (4.4)	7668 (4.5)
Smoker, n (%)		16,948 (8.1)	14,668 (8.6)
Diabetes type, n (%)	Type 2	206,591 (99.3)	169,407 (99.3)
	Type 1	1271 (0.6)	1009 (0.6)
	Other (eg gestational, monogenic, drug-induced, secondary diabetes)	240 (0.1)	233 (0.1)
Diabetes medications, n (%)	Oral glucose-lowering medications only	129,124 (62.1)	119,236 (69.9)
	Insulin preparations only	7419 (3.6)	6624 (3.9)
	Oral glucose-lowering medications and insulin preparations	35,067 (16.9)	32,819 (19.2)
Hypertension, n (%)		175,059 (84.1)	150,443 (88.2)
Mean systolic blood pressure, mm Hg (SD)		133.7 (14.8)	133.7 (14.6)
Mean diastolic blood pressure, mm Hg (SD)		70.4 (8.2)	70.4 (8.2)
Hyperlipidemia, n (%)		179,434 (86.2)	157,862 (92.5)
Established cardiovascular disease, n (%)		70,952 (34.1)	61,680 (36.1)

Table 6 Individuals Meeting Process Indicators

Process Indicator	2013	2014	2015	2016	2017	2018	2019
≥ 2 Body weight measurements	14,173 (17.4)	53,404 (60.0)	61,271 (65.1)	67,892 (68.8)	80,331 (82.0)	98,263 (83.7)	103,193 (83.5)
≥ 2 HbA1c tests	68,877 (84.7)	72,320 (81.3)	77,508 (82.3)	82,324 (83.4)	84,460 (86.2)	96,288 (82.0)	100,090 (81.0)
≥ 2 blood pressure measurements	69,491 (85.5)	66,035 (74.2)	75,089 (79.7)	79,086 (80.1)	89,114 (90.9)	109,443 (93.2)	115,218 (93.2)
≥ 1 LDL-c measurements	71,229 (87.6)	75,285 (84.6)	80,960 (86.0)	85,882 (87.0)	86,285 (88.1)	100,703 (85.8)	105,146 (85.1)
≥ 1 Eye assessment^a	50,455 (62.1)	57,056 (64.1)	60,853 (64.6)	65,744 (66.6)	65,465 (66.8)	70,671 (60.2)	74,944 (60.6)
≥ 1 Kidney assessment^b	74,633 (91.8)	80,245 (90.2)	86,089 (91.4)	91,131 (92.3)	91,605 (93.5)	109,720 (93.5)	115,969 (93.8)
≥ 1 Foot assessment^c	47,182 (58.0)	48,654 (54.7)	53,562 (56.9)	59,822 (60.6)	58,275 (59.5)	63,601 (54.2)	62,679 (50.7)

Notes: ^aEye assessment = Diabetic retinal photography (DRP) AND/OR visit to an ophthalmologist. ^bKidney assessment = Serum creatinine/eGFR AND/OR urine albumin–creatinine ratio (UACR) AND/OR urine protein–creatinine ratio (UPCR). ^cFoot assessment = Diabetic foot screen (DFS) AND/OR visit to a podiatrist.

Figure 2 Distribution of mean HbA1c for individuals in the SDR in each year.