Use of Linked Nordic Registries for Population Studies in Hematologic Cancers: The Case of Multiple Myeloma

Figures & data

Figure 1 Identification of the multiple myeloma population who were diagnosed from 2010 to 2018 using national registries in Denmark, Finland, and Sweden.

Notes: Data were obtained from national healthcare registries between January 1, 2005, through October 31, 2018. However, 2005 to 2009 was a washout period to ensure patients registered in 2010 were not diagnosed before 2010. Dotted lines represent the timeframe for identification of patients with an MM diagnosis within each country’s registries. *CR checked if diagnosis date was missing from NPR.

Abbreviations: CDR, cause of death registry; CR, cancer registry; NPR, national patient registry; PDR, prescribed drug registry.

Table 1 Comparison of the National Patient Registries for Denmark, Finland, and Sweden

	Denmark	Finland	Sweden
Name	Landspatientregisteret^Citation18	HILMO^Citation19 AvoHILMO^Citation20	Patientregistret^Citation21
Start date	Founded in 1977, complete nationwide coverage reached in 1978	HILMO founded in 1967, complete nationwide coverage since inception AvoHILMO founded in 2011	Founded in 1964, complete nationwide coverage reached in 1997
Data owner	Sundhedsdatastyrelsen (National Board of Health Data)	THL (National Institute for Health and Welfare)	Socialstyrelsen (National Board of Health and Welfare)
Healthcare department	Secondary care	Secondary care (HILMO) Primary care (AvoHILMO)	Secondary care
Definition of observation	One treatment episode	One visit	One visit
Coding nomenclature	ICD-10/ICPC-2 for diagnoses/reason for visit NCSP for medical procedures, includes hospital-administered drugs DRG/DAGS for reimbursement	ICD-10/ICPC-2 for diagnoses/reason for visit NCSP for medical procedures DRG for reimbursement	ICD-10 for diagnoses/reason for visit KVÅ for medical procedures DRG for reimbursement

Abbreviations: AvoHILMO, National Care Registry for Primary Healthcare Institutions; DAGS, Danish Outpatient Grouping System; DRG, Diagnosis Related Groups; HILMO, National Care Registry for Health Care Institutions; ICD-10, International Classification of Diseases 10th Revision; ICPC-2, International Classification of Primary Care 2nd Edition; KVÅ, Koder ur Klassifikation av vårdåtgärder (classification of care measures); NCSP, Nordic Classification of Surgical Procedures.

Table 2 Comparison of the Prescription Drug Registries for Denmark, Finland, and Sweden

	Denmark	Finland	Sweden
Name	Lægemiddelstatistikregisteret^Citation22	Sairasvakuutuksesta korvattavat lääketoimitukset^Citation23	Läkemedelsregistret^Citation24
Data owner	Sundhedsdatastyrelsen	Kela (National Social Insurance Institution)	Socialstyrelsen
Start date	1994	1994	2005
Pharmaceuticals included	Nationally reimbursed medications prescribed through community pharmacies Primarily inexpensive medications; hospital drugs not included	Prescription drugs purchased within the reimbursement scheme OTC drugs and hospital drugs not included	All prescriptions picked up in all pharmacies OTC drugs and hospital drugs not included

Abbreviation: OTC, over the counter.

Table 3 Comparison of the Cancer Registries for Denmark, Finland, and Sweden

	Denmark	Finland	Sweden
Name	Cancerregisteret^Citation25	Suomen Syöpärekisteri^Citation26	Socialstyrelsen^Citation27
Data owner	Sundhedsdatastyrelsen	THL	Socialstyrelsen
Start date	Founded in 1942 Reporting mandatory since 1987	Founded in 1953 Reporting mandatory since 1961	Founded in 1958 Reporting mandatory from the start

Abbreviation: THL, Terveyden ja hyvinvoinnin laitos.

Figure 2 Patient cohorts with newly diagnosed multiple myeloma across Denmark, Finland, and Sweden from 2010 to 2018.

Notes: Includes patients with a diagnosis of NDMM identified in the raw dataset with C90.0 recorded in the NPR and/or the CR, and who were prescribed MM-specific treatment recorded in the PDR.

Abbreviations: CR, Cancer Registry; MM, multiple myeloma; NPR, National Patient Registry.

Table 4 First-Line Treatment and Diagnostic Characteristics of Patients in Sweden Identified as Being Registered in Both the NPR and CR (NPR+/CR+) and Those Being Registered in Only the NPR (NPR+/CR−)

	NPR+/CR+			NPR+/CR−
	Total (N = 2672)	ASCT (n = 588)	Non-ASCT (n = 2084)	Total (N = 550)	ASCT (n = 103)	Non-ASCT (n = 447)
Bortezomib
Patients, n (%)	335 (12.5)	110 (18.7)	225 (10.8)	79 (14.4)	20 (19.4)	59 (13.2)
Registrations, n	2568	744	1824	657	108	549
Lenalidomide^a
Patients, n (%)	1428 (53.4)	457 (77.7)	971 (46.6)	256 (46.5)	79 (76.7)	177 (39.4)
LenDex patients, n (%)	787 (29.5)	303 (51.5)	484 (23.2)	154 (28.0)	51 (49.5)	103 (23.0)
LenDex registrations, n	6454	2611	3843	1144	381	763
Diagnosis location
Inpatient visit, n (%)	966 (36.2)	–	–	168 (30.5)	–	–
Outpatient visit, n (%)	1706 (63.8)	–	–	382 (69.5)	–	–

Notes: ^aLenDex, combination of lenalidomide and dexamethasone.

Abbreviations: ASCT, autologous stem cell transplantation; CR, Cancer Registry; NPR, National Patient Registry.

Figure 3 Identification of patients with MM in Sweden. Patients identified in the NPR or CR are designated “+” and those not identified “−”.

Notes: *After discussions with the therapy experts a restriction of the time period for data collection from 2010 to 2016 was agreed upon in order to capture the relevant follow-up time. The investigation of NPR+/CR– cohort was continued on this new cohort. **The two groups are not mutually exclusive; some patients could be excluded for both reasons.

Abbreviations: CR, Cancer Registry; MM, multiple myeloma; NPR, National Patient Registry.

Figure 4 Bortezomib registration pattern in Denmark based on days of registration.

Notes: Bortezomib should be administered once weekly (7 days between administrations) for 4 weeks with a 1-week gap (7-7-7 [14] 7-7-7 cycle). There is also a scheme to administer (and register) bortezomib twice weekly, ie, 3 to 4 days between treatments and a gap of 10 to 11 days. In most cases, bortezomib was administered at 3, 4, 10, 11, or 14 days between registrations.

Table 5 Registration of Drugs Commonly Prescribed with Bortezomib in Denmark

	Patients
Bortezomib	838 (100%)
Bortezomib and >1 melphalan	182 (21.7%)
Bortezomib and >1 cyclophosphamide	87 (10.4%)
Bortezomib and >1 thalidomide	48 (5.7%)
Bortezomib and >1 lenalidomide	14 (1.7%)

Table 6 MM-Specific Drug Registrations in Finnish Registries

Drug	National Patient Registries				Prescription Drug Registry^a
	HILMO		AvoHILMO
	Number of Registrations (=Frequency)	Distinct Patients (n)	Number of Registrations (=Frequency)	Distinct Patients (n)	Number of Registrations (=Frequency)	Distinct Patients (n)
L01AA03 Melphalan	0	0	430	176	2187	604
L01XX32 Bortezomib	0	0	242	135	0	0
L04AX02 Thalidomide	0	0	323	99	1987	381
L04AX04 Lenalidomide	0	0	1135	339	7760	953

Notes: ^aPrescription Drug Registry contains reimbursed purchases, not limited by reimbursement code.

Abbreviations: AvoHILMO, National Care Registry for Primary Healthcare Institutions; HILMO, National Care Registry for Health Care Institutions; MM, multiple myeloma.

Table 7 Determining Incidence and Prevalence of Newly Diagnosed Multiple Myeloma in Finland from 2010 to 2016 per 100,000 Individuals: NPR and CR. Results are Provided Separately for Treated and Untreated Patients Who Were Identified in Both Registries (NPR+/CR+) and for Treated Patients Who Were Identified in the NPR but Not in the CR (NPR+/CR−)

	Treated and Untreated		Treated
	NPR+/CR+		NPR+/CR−
	Incidence	Prevalence	Incidence	Prevalence
2016	5.4	27.7	2.9	24.9
2015	5.1	27.4	3.7	25.6
2014	6.0	27.3	4.3	25.6
2013	5.3	26.8	4.5	24.9
2012	5.7	26.4	4.5	23.9
2011	5.9	25.4	4.7	22.3
2010	6.9	23.7	5.5	19.7

Abbreviations: CR, Cancer Registry; NPR, National Patient Registry.

Table 8 Determining Incidence and Prevalence of Newly Diagnosed Multiple Myeloma in Sweden from 2010 to 2016 per 100,000 Individuals: NPR and CR. Results are Provided Separately for Treated and Untreated Patients Who Were Identified in Both Registries (NPR+/CR+) and for Treated Patients Who Were Identified in the NPR but Not in the CR (NPR+/CR−)

	Treated and Untreated		Treated
	NPR+/CR+		NPR+/CR−
	Incidence	Prevalence	Incidence	Prevalence
2016	5.8	38.1	1.8	7.2
2015	6.6	37.8	1.3	6.2
2014	6.7	36.9	1.1	5.6
2013	6.4	35.4	1.1	5.5
2012	6.3	34.6	0.9	5.2
2011	6.5	33.2	1.1	5.4
2010	6.7	31.9	0.9	5.2

Abbreviations: CR, Cancer Registry; NPR, National Patient Registry.

Table 9 Best Estimate of Incidence and Prevalence of NDMM in Denmark, Finland, and Sweden from 2010 to 2016 per 100,000 Individuals

	Denmark		Finland		Sweden
	Incidence	Prevalence	Incidence	Prevalence	Incidence	Prevalence
2016	7.3	37.1	6.4	35.2	7.6	45.2
2015	7.3	35.6	6.2	34.3	7.8	44.0
2014	6.9	33.7	7.1	33.6	7.7	42.5
2013	7.2	31.7	6.5	32.1	7.4	40.9
2012	6.3	29.8	6.9	31.1	7.2	39.8
2011	6.3	28.3	7.1	29.2	7.6	38.5
2010	5.8	26.9	7.9	26.5	7.6	37.1

Notes: Best estimate is calculated using CR and NPR. Finland: CR+ and NPR+ (treated and untreated) + NPR+ and CR– (treated). Denmark: CR+ and NPR+ (treated and untreated). Sweden: “CR+ and NPR+ (treated and untreated)” + NPR+ and CR– (treated). Incidence and prevalence rates were calculated as crude numbers divided by the total national population retrieved from Statistics Sweden, Statistics Denmark, and Statistics Finland. The best estimate of incidence and prevalence is considered to be sum of NPR+/CR+ treated and untreated + NPR+/CR– treated as shown in Table 7. Best estimate was calculated by adding patients found in both the NPR and CR – both treated and untreated patients with number of treated patients in the NPR who are not found in the CR.

Abbreviations: CR, Cancer Registry; NDMM, newly diagnosed multiple myeloma; NPR, National Patient Registry.

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