Rheumatoid interstitial lung disease in Canterbury, Aotearoa New Zealand - A retrospective cohort study

BACKGROUND

Rheumatoid arthritis associated interstitial lung disease (RA-ILD), is an important extra-articular manifestation of rheumatoid arthritis (RA). The frequency, risk factors, and prognosis of RA-ILD are incompletely understood.

AIMS

To determine the prevalence and incidence, clinical characteristics and risk factors for development, and outcomes of persons with RA-ILD in the population of the Canterbury District Health Board (CDHB) catchment area.

METHODS

Individuals aged ≥ 18 years with RA, resident in the CDHB catchment area between 1 January 2006 and 31 December 2008 (Period One), and 1 January 2011 to 31 December 2013 (Period Two) were identified by medical record review and followed until 30 June 2019. Individuals with RA-ILD as defined by pre-specified criteria were identified. The association between demographic and clinical characteristics and RA-ILD development and mortality was examined using Cox-proportional hazards models.

RESULTS

The prevalence of RA-ILD per 100,000 was 10.97 (95 % CI 7.53,14.42) for Period One, and 14.74 (95 % CI 10.84,18.63) for Period Two. Among individuals evaluated for risk factors for RA-ILD development, the estimated cumulative incidence of ILD at 10 years was 4.47 % (95 % CI 3.14, 6.14). After adjusting for age, rheumatoid factor positivity (HR 3.73, 95 % CI, 1.32,10.56), extra-articular manifestations other than RA-ILD (HR 4.48, 95 % CI 2.36,8.48), and subcutaneous rheumatoid nodules (HR 4.66, 95 % CI 2.34, 9.26) were associated with increased risk of developing RA-ILD. The standardised mortality ratio for RA-ILD was 3.90 (95 % CI 2.55,5.72) compared to the general population. Extent of ILD on CT chest was associated with mortality (HR for >20% vs. < 20 % 4.47, 95 % CI 1.67,11.96).

CONCLUSIONS

Clinically evident RA-ILD occurred in approximately 5 % of individuals with RA. Mortality was increased almost fourfold compared to the general population. Radiologic extent was the most important prognostic factor.

Care of patients with early inflammatory arthritis in the Wellington region according to the British Society of Rheumatology's best practice tariff standards

AIM

To compare the care of patients with suspected early inflammatory arthritis (EIA) in the Wellington region with the quality standards from the British Society of Rheumatology (BSR) 2013/14 best practice tariffs.

METHODS

The case notes for patients first seen in clinic from the beginning of 2015 were reviewed until at least 100 cases of suspected inflammatory arthritis were identified. Data gathered included the length of time from referral to first specialist rheumatology clinic, the length of time from referral to the commencement of disease modifying therapy for cases of inflammatory arthritis and the number of specialist-led clinics within the first 12 months of the first appointment.

RESULTS

117 cases of suspected inflammatory arthritis were reviewed. The median time from referral to the first appointment was 11.4 weeks (IQR 6.6-13.3). 61 of the 117 cases had clinically confirmed EIA. The median time from referral to the commencement of disease-modifying therapy was 10.5 weeks (IQR 5-15). For confirmed EIA, the median number of clinics in the first year was four (IQR 3-4).

CONCLUSION

Patients with suspected inflammatory arthritis in the Wellington region wait much longer to be seen than is recommended by the BSR guidelines.

Incidence of anti-neutrophil cytoplasmic antibody-associated vasculitis before and after the February 2011 Christchurch Earthquake

BACKGROUND

It has been suggested that environmental pollution from an earthquake might be associated with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).

AIM

To determine the incidence of AAV during the 3-year period before (period 1), and the 3 years following (period 2), the earthquake that occurred on 22 February 2011 in Christchurch, New Zealand.

METHODS

All ANCA tests performed in the Canterbury region for 3 years before the earthquake (period 1, 2007-2010), and for 3 years after the earthquake (period 2, 2011-2014) were examined. AAV was defined according to The European Medicines Agency classification algorithm. Medical records were reviewed and cases were included if they were newly diagnosed within the study period. Incidence was calculated using population data from the 2013 New Zealand census.

RESULTS

A total of 52 new cases of AAV was identified. The incidence in period 1 was 1.87/100 000/annum (95% C.I. 1.23-2.72), and for period 2 was 1.73/100 000/annum (95% C.I. 1.12-2.55). There was no statistically significant difference in incidence between the two study periods. There was no difference when analysing by myeloperoxidase (MPO) or proteinase-3 status, or restricting the analyses to those residing in an urban environment. The mean age at diagnosis for MPO AAV was significantly younger in period 2 than period 1 (61 years vs 71 years, P = 0.05). There were no other clinically important differences between the two groups.

CONCLUSION

This study does not support the hypothesis that an environmental agent, caused by dust pollution related to earthquake damage, has a causative role in the pathogenesis of AAV.

Renin: activity, reactivity and concentration in a population survey. Relationship to blood pressure

Plasma renin activity (PRA), plasma renin reactivity (PRR) and plasma re nin concentration (PRC) were measured in 47 normotensive and 4 hyperten sive subjects, none of whom were taking medication. There was a significant negative correlation between PRC and PRR of plasma. Contrary to previous reports, PRR was not increased in subjects with hypertension. The most significant finding was the negative correlation of PRC and PRA with blood pressure in normotensive subjects, but the lack of such a correlation in hypertensive subjects. This finding, plus the significantly higher PRC in hypertensive subjects, suggests a deficient suppression of renin release in hypertensive individuals.

The renin-renin substrate reaction, as it occurs in the plasma, is illustrated below (Fig. 1). Renin, a proteolytic enzyme, released from the juxtaglomerular cells of the kidney, acts upon its α2 globulin tetradecapeptide renin substrate, splitting the leucyl-leucine bond, thus causing the release of angiotensin I (AI). AI, a decapeptide, is substrate for yet another enzymatic reaction, being converted in turn to angiotensin II (AII), by the converting enzymes present in lung and plasma. This reaction sequence is undoubtedly oversimplified since it does not take into account a number of observations, the first of which was made in 1964 by Boucher and co-workers; namely that when equal amounts of purified renin were added in vitro to the plasma of different individuals, there were significant variations in the quantity of angiotensin generated.1 From this, as well as from later studies, the concept developed that plasma contained a renin inhibitor.2 These earlier observations were supported and extended by studies from Laragh's group, which reported that the plasma of patients on oral contraceptives produced exaggerated amounts of AI upon the addition of exogenous renin3,4, and these authors have referred to this phenomenon as the renin reactivity of plasma. Increased renin reactivity has since been reported in plasma of patients with essential hypertension,5, 6, 7 primary aldosteronism 8 and renovascular hypertension.6 Thus, it has been thought that this phenomenon may play a role in the hypertensive process. If reactivity of plasma is increased in the above named situations (i.e., if there is exaggerated generation of AI upon the addition of purified renin), then it follows that in vivo AI generation or AI generation on incubation of plasma at 37° should also be increased relative to the amount of endogenous renin present. Thus the ratio of plasma renin activity (PRA) to plasma renin concentration (PRC) should be greater in women on oral contraceptives,9, 10 as well as in people with the several varieties of hypertension mentioned above. The present report concerns itself, in part, with the measurement of the PRA: PRC ratio (which we use to express the reactivity of plasma) in normal and hypertensive subjects, as well as in subjects taking either estrogen-con taining compounds or various antihypertensive medications. Our results con firm the observation that considerable variation in plasma reactivity does ex ist, and that there is increased reactivity in plasma of women on oral contra ceptives or estrogen-containing compounds. Unexpected was the discovery that reactivity is inversely related to the concentration of renin. Our studies, however, failed to find increased reactivity in subjects with hypertension, and thus do not support the concept of an important role for a renin inhibitor or modifier in essential hypertension. Most important, however, was our discov ery of a highly significant inverse correlation of both PRA and PRC with blood pressure in normal people. The lack of such a correlation, as well as the finding of elevated PRC in subjects with hypertension, suggests that the person with elevated blood pressure lacks the normal capacity to diminish renin secretion.