Table 3

Validation of diagnoses in the Swedish Inpatient Register by Positive Predictive Values (PPVs)

Diagnosis

Correct diagnosis in the IPR (%) = positive predictive value (PPV)

Comment

Main Author

PubMed ID

Year

Gold Standard (reference)


Cardiovascular disease

Myocardial infarction

36/36 (100)

Only primary diagnoses were evaluated.

NPV = 861/864 (99.7)

Nilsson [7]

8114596

1994

MR

Myocardial infarction

2053/2101 (98)

Patients aged 45 - 70 years in 1992 - 1994.

Linnersjö[34]

11121592

2000

MR

Angina Pectoris

18/19 (95)

Only primary diagnoses were evaluated.

NPV = 879/881 (99.8)

Nilsson [7]

8114596

1994

MR

Heart failure (HF)

259/317 (81.7)

Definition of HF proposed by the European Society of Cardiology [35].

Restricting the diagnosis HF to the primary diagnosis, then 133/140 (95.0%) were correct.

Ingelsson [36]

15916919

2005

ULSAM

Heart failure

15/17 (88)

Only primary diagnoses were evaluated.

NPV = 876/883 (99.2)

Nilsson [7]

8114596

1994

MR

Atrial fibrillation (using ICD-codes for atrial fibrillation or atrial flutter)

97/100 (97)

95 individuals had ECGs consistent with atrial fibrillation. Two patients had no ECGs available but were regarded as having atrial fibrillation on the basis of medical records.

Smith [37]

19936945

2009

MR + Electrocardiograms (ECG)

Non-fatal strokes

3492/5101 (68.5)

Patients aged 25-74 years in 1985-89. Criteria for acute stroke in this study were based on WHO criteria.

Stegmayr [38]

1291884

1992

MONICA-population based stroke register

Stroke/Transient ischemic Attack

207/210 (98.6)

ULSAM

Wiberg

(PC, Feb 12)

ULSAM

Gestational hypertension

108/111 (97.3)

Zetterström

(PC, March 3)

MR

Gestational hypertension

97/115 (84.3)

Ros [39]

9620050

1998

MR

Vascular interventions (for lower limb ischemia)

545/546 (99.8)

Hultgren [40]

11170873

2001

MR

Autoimmune/immune-mediated diseases

Rheumatoid arthritis (RA)

489/510 (95.9)

Malmö, Sweden, 1990-1994. According to the RA criteria of the American College of Rheumatology [41].

Turesson [42]

10461483

1999

MR

Rheumatoid arthritis

Without lymphoma: 440/505 (87.1)

With lymphoma: 386/413 (93.5)

In 40 of the 386 cases with lymphoma, medical records did not include enough information to evaluate whether the RA criteria of the American College of Rheumatology were fulfilled but all available information supported the diagnosis of RA

Baecklund [22]

16508929

2006

MR

Wegener's granulomatosis

68/78 (87)

American College of Rheumatology diagnostic criteria [43]

Knight [12]

12115591

2002

MR

Celiac disease

66/77 (86) of patients with later lymphoma

Only in 8 patients could celiac disease be ruled out. In 3 patients, the chart reviews were consistent with possible celiac disease.

Ekström-Smedby [44]

15591504

2005

MR

Primary adrenocortical insufficiency

105/133 (78.9)

Bensing [45]

18727712

2008

Patients tested positive for 21-OH autoantibodies

Diabetes mellitus (type 1 and 2)*

22/28 (79)

Only primary diagnoses were evaluated.

NPV = 872/872 (100)

Nilsson [7]

8114596

1994

MR

Both diabetes (type 1 or 2) and foot ulcer*

235/236 (99.6) admissions were correct with regards to ICD-coding

117 patients with deep foot infections and type 1 or 2 diabetes, who had been referred to a multidisciplinary foot-care team at Lund University Hospital.

Ragnarson-Tennvall [46]

11123504

2000

MR

Inflammatory bowel disease (IBD)

4778/6440 (74)

1965-1983.

Due to the ICD-classification used at this time, ulcerative colitis could not be distinguished from Crohn's disease, and therefore "overall IBD" was evaluated

Ekbom [47]

1985033

1991

MR + histopathological reviews

Psychiatric disease and neurology

Schizophrenia

94/100 (94.9)

Review of medical records with structured diagnostic interviews

Ekholm [48]

16316898

2005

MR

Schizophrenia

78/91 (85.7)

Individuals born 1973-77.

DSM-IV criteria for schizophrenia syndrome

Dalman [49]

12395142

2002

MR

Schizophrenia

106/111 (95.5)

Review of 121 consecutive cases in one city using a structured DSM-IV checklist, 111 records obtained

Hultman [50]

16863597

2006

MR

Schizophrenia,

schizophreniform disorder or schizoaffective disorder

94/168 (56)

Primary diagnoses that fulfilled DSM-IV criteria (OPCRIT algorithm)

Reutfors [51]

-

2009

MR

Schizophrenia †

78/104 (75.0)

to

85/104 (81.7)

104 patients discharged in 1971 with a diagnosis of schizophrenia. DSMIII-criteria were used for this validation. From Stockholm County IPR. A strict review found a PPV of 75%. This figure increased to 85% when some lack of information was accepted (less strict criteria).

Kristjansson [52]

-

1987

MR

Schizophrenia

(Kappa = 0.37 correlating to an agreement rate of 68%)

All individuals with a diagnosis of schizophrenia in the IPR and who had an inpatient forensic psychiatric assessment using a national register of all such evaluations from 1988-2000 (n = 1638).

Fazel [25]

19454640

2009

Forensic psychiatric assessment

Schizophrenia

34/44 (77%)

Bergman [53]

-

1999

Four-week- inpatient assessment in forensic psychiatry department

Alzheimer

54/75 (72)

Jin [54]

15326258

2004

Clinical work-up following phone interview

Personality disorders

37/40 (92)

Random sample of 40 individuals out of 401 violent offenders with personality disorders from a longitudinal study

Grann [55]

-

1998

MR

Personality disorders

30/55 (55%)

Bergman [53]

-

1999

Four-week- inpatient assessment in forensic psychiatry department

Guillain-Barré Syndrome (GBS)

69/83 (83)

83% of patients fulfilled the National Institute of Neurological and Communicative Disorders and Stroke criteria for GBS [56]. PPV of first primary diagnosis with GBS was 84%; and for secondary diagnosis 75%.

Jiang [57]

7785420

1995

MR

Herpes simplex encephalit

223/638 (35.0)

1990-2001

Hjalmarsson [58]

17806053

2007

Laboratory data (positive finding of HSV-1)

Trauma and fractures

Brain concussion

18/18 (100)

Only primary diagnoses were evaluated.

NPV = 880/882 (99.8)

Nilsson [7]

8114596

1994

MR

Hip fracture

21/22 (95)

Only primary diagnoses were evaluated.

NPV = 877/878 (99.9)

Nilsson [7]

8114596

1994

MR

Hip fracture

2556/2597 (98.4)

Cases derived both from IPR and operation registers.

Michaelsson [59]

9632404

1998

MR

Injuries

1299/1370 (94.8)

Injury code was correct at 3-digit-level.

Gedeborg

-

(PC, Feb 3)

MR

Surgical procedures (and related medical conditions)

Major amputations (leg and arm)

610/624 (97.8)

Unique number of amputations was 610 in 624 patients.

Malmstedt

(PC, Feb 24)

MR

Appendicitis†

1661/1840 (90.3)

Performed in the Jönköping county. Incidental appendectomies were excluded. The IPR overestimated the prevalence of appendicitis with 6%. The negative predictive value of appendicitis was 94.0% and the accuracy 91.3%†

Andersson [60]

8298378

1994

Histological examination of excised tissue (in patients undergoing appendectomy)

Inguinal hernia

17/18 (94)

Only primary diagnoses were evaluated.

NPV = 882/882 (100)

Nilsson [7]

8114596

1994

MR

Other disorders

Achalasia

67/83 (81)

Zendehdel [61]

17488250

2007

MR

Prostate hyperplasia

14/14 (100)

Only primary diagnoses were evaluated.

NPV = 882/886 (99.5)

Nilsson [7]

8114596

1994

MR

Asthma

14/15 (93)

Only primary diagnoses were evaluated.

NPV = 885/885 (100)

Nilsson [7]

8114596

1994

MR

Abdominal pain (observation for abdominal pain)

33/37 (89)

Only primary diagnoses were evaluated.

NPV = 860/863 (99.7)

Nilsson [7]

8114596

1994

MR

Preeclampsia

137/148 (92.6)

Ros [39]

9620050

1998

MR

Endometriosis

Without ovarial cancer: 615/628 (97.9% correct).

With ovarial cancer: 220/225 (97.8% correct)

Melin

-

(PC, Feb 3)

MR

Foot ulcer (only)

249/250 (99.6) admissions to hospital were correct with regards to ICD-coding

Based on 117 patients with deep foot infections and type 1 or 2 diabetes, referred to multidisciplinary foot-care team. Specificity for foot ulcers and concomitant diabetes was 98%.

Ragnarson-Tennvall [46]

11123504

2000

MR

Connective tissue disease (CTD)

71/91 (78%)

In this study CTD included rheumatoid arthritis, systemic lupus erythemathosus, sclerodermia, Sjögren's syndrome, dermatomyositis, polymyositis etc.

Nyren [62]

9492663

MR

Acute pancreatitis

695/602 (98.8)

Among 602 patients with a primary or secondary diagnosis of acute pancreatitis in the IPR. 84.0% had a definitive acute pancreatitis and another 14.8% a probable acute pancreatitis.

Lindblad

(PC, Feb 6)

MR + laboratory tests and radiological imaging


PC, Personal communication: All personal communications took place in 2010 (exact date is listed in the table).

CDT, Connective tissue disease. GBS, Guillain-Barré Syndrome; HF, Heart Failure, IBD, Inflammatory bowel disease. IPR, Inpatient Register.

MR, compared with Medical Records (patient charts).

PPV, Positive Predictive Value.

NPV, Negative Predictive Value.

ULSAM, Uppsala Longitudinal Study of Adult Men) cohort.

*From ICD-7 through ICD-9, no distinction was made between type 1 and type 2 diabetes. For practical reasons "diabetes" has been listed as an autoimmune disorder.

† These studies took place when the county in question did not yet report inpatient data to the IPR, but results are deemed valid for the IPR.

Ludvigsson et al. BMC Public Health 2011 11:450   doi:10.1186/1471-2458-11-450

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