Table 3 Validation of diagnoses in the Swedish Inpatient Register by Positive Predictive Values (PPVs)

Myocardial infarction

36/36 (100)

Only primary diagnoses were evaluated.

NPV = 861/864 (99.7)

Myocardial infarction

2053/2101 (98)

Angina Pectoris

18/19 (95)

Only primary diagnoses were evaluated.

NPV = 879/881 (99.8)

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.

Heart failure

15/17 (88)

Only primary diagnoses were evaluated.

NPV = 876/883 (99.2)

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.

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.

Stroke/Transient ischemic Attack

207/210 (98.6)

ULSAM

Gestational hypertension

108/111 (97.3)

Gestational hypertension

97/115 (84.3)

Vascular interventions (for lower limb ischemia)

545/546 (99.8)

Rheumatoid arthritis (RA)

489/510 (95.9)

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

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

Wegener's granulomatosis

68/78 (87)

American College of Rheumatology diagnostic criteria [43]

Celiac disease

66/77 (86) of patients with later lymphoma

Primary adrenocortical insufficiency

105/133 (78.9)

Diabetes mellitus (type 1 and 2)*

22/28 (79)

Only primary diagnoses were evaluated.

NPV = 872/872 (100)

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.

Inflammatory bowel disease (IBD)

4778/6440 (74)

Schizophrenia

94/100 (94.9)

Review of medical records with structured diagnostic interviews

Schizophrenia

78/91 (85.7)

Individuals born 1973-77.

DSM-IV criteria for schizophrenia syndrome

Schizophrenia

106/111 (95.5)

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

Schizophrenia,

schizophreniform disorder or schizoaffective disorder

94/168 (56)

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

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).

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).

Schizophrenia

34/44 (77%)

Alzheimer

54/75 (72)

Personality disorders

37/40 (92)

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

Personality disorders

30/55 (55%)

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%.

Herpes simplex encephalit

223/638 (35.0)

1990-2001

Brain concussion

18/18 (100)

Only primary diagnoses were evaluated.

NPV = 880/882 (99.8)

Hip fracture

21/22 (95)

Only primary diagnoses were evaluated.

NPV = 877/878 (99.9)

Hip fracture

2556/2597 (98.4)

Cases derived both from IPR and operation registers.

Injuries

1299/1370 (94.8)

Injury code was correct at 3-digit-level.

Major amputations (leg and arm)

610/624 (97.8)

Unique number of amputations was 610 in 624 patients.

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%†

Inguinal hernia

17/18 (94)

Only primary diagnoses were evaluated.

NPV = 882/882 (100)

Achalasia

67/83 (81)

Prostate hyperplasia

14/14 (100)

Only primary diagnoses were evaluated.

NPV = 882/886 (99.5)

Asthma

14/15 (93)

Only primary diagnoses were evaluated.

NPV = 885/885 (100)

Abdominal pain (observation for abdominal pain)

33/37 (89)

Only primary diagnoses were evaluated.

NPV = 860/863 (99.7)

Preeclampsia

137/148 (92.6)

Endometriosis

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

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

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%.

Connective tissue disease (CTD)

71/91 (78%)

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

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.