A validation of register-derived diagnoses of interstitial lung disease in patients with inflammatory arthritis: data from the NOR-DMARD study

OBJECTIVE

There is a lack of knowledge concerning the validity of the interstitial lung disease (ILD) diagnoses used in epidemiological studies on rheumatic diseases. This paper seeks to verify register-derived ILD diagnoses using chest computed tomography (CT) and medical records as a gold standard.

METHOD

The Norwegian Anti-Rheumatic Drug Register (NOR-DMARD) is a multicentre prospective observational study of patients with inflammatory arthritis who start treatment with disease-modifying anti-rheumatic drugs. NOR-DMARD is linked to the Norwegian Patient Registry (NPR) and Cause of Death Registry. We searched registers for ILD coded by ICD-10 J84 or J99 among patients with rheumatoid arthritis, psoriatic arthritis, or spondyloarthritis. We extracted chest CT reports and medical records from participating hospitals. Two expert thoracic radiologists scored examinations to confirm the ILD diagnosis. We also searched medical records to find justifications for the diagnosis following multidisciplinary evaluations. We calculated the positive predictive values (PPVs) for ILD across subsets.

RESULTS

We identified 71 cases with an ILD diagnosis. CT examinations were available in 65/71 patients (91.5%), of whom ILD was confirmed on CT in 29/65 (44.6%). In a further 10 patients, medical records confirmed the diagnosis, giving a total of 39/71 verified cases. The PPV of a register-derived ILD diagnosis was thus 54.9%. In a subset of patients who had received an ILD code at two or more time-points and had a CT scan taken within a relevant period, the PPV was 72.2%.

CONCLUSION

The validity of register-based diagnoses of ILD must be carefully considered in epidemiological studies.

Familial intestinal degenerative neuropathy associated with chronic intestinal pseudo-obstruction

BACKGROUND

Few families with autosomal dominant forms of chronic idiopathic pseudo-obstruction (CIP) have been identified and reported.

METHODS

We compared two families by clinical, laboratory, histopathologic, and genealogical investigations. Ten patients (pts) (five women) from two families, A and B, both with a family history suggesting autosomal dominant CIP, were investigated.

KEY RESULTS

All pts had chronic diarrhea, nine of ten pts had chronic abdominal pain and seven of ten chronic vomiting. Median age for onset of symptoms was 23 (A) and 34 years (B). None had dysphagia, urogenital, neurologic, or ocular symptoms. Small bowel transit and jejunal culture were abnormal in eight of nine. Manometry showed severe jejunal hypomotility in the fasting and fed state and absence of normal phase III in all nine pts and neuropathy-like duodenal alterations in eight of nine. Progress to overt CIP had occurred in six pts. Histopathologic re-evaluation (three pts) showed that criteria of visceral degenerative neuropathy were fulfilled in both families including intranuclear inclusions in all three pts. Genealogic exploration using the unique Swedish Register for Catechetical Meetings disclosed that the two families with all likelihood shared a male ancestor in the 1890 s.

CONCLUSIONS & INFERENCES

The compiled results with striking similarities between family A and B together with genealogy findings indicate that this is one, large kindred with a familial autosomal dominant form of intestinal degenerative neuropathy often progressing to CIP but without extra-intestinal manifestations. This is the fourth and, so far, the largest family reported with these characteristics.