Epidemiology of giant cell arteritis in Waikato, Aotearoa New Zealand.

AIM: Giant cell arteritis (GCA) is the most common primary vasculitis in adults over 50 years of age. Our primary objective was to assess the incidence and prevalence of GCA in Waikato in a bid to deepen our understanding of the epidemiology of GCA in Aotearoa New Zealand. METHODS: From January 2014 to December 2022, cases of GCA were identified prospectively and retrospectively through temporal artery ultrasound request lists and temporal artery biopsy histology reports. Using electronic health records, data were collected retrospectively on patient demographics and clinical features. These were used to calculate the incidence, prevalence and standardised mortality ratio (SMR) of GCA in Waikato. RESULTS: There were 214 patients diagnosed with GCA over the 9-year period. The majority of patients were European (93.9%, 201/214) with Maori patients being significantly younger than European patients. The mean annual incidence of clinical GCA was 14.7 per 100,000 people over 50 years (95% confidence interval [CI] 12.7-16.6). The SMR was 1.18 (95% CI 0.83-1.52). CONCLUSION: This is the largest study to date on the epidemiology of GCA in Aotearoa New Zealand. The incidence of GCA is comparable to other studies performed in Aotearoa New Zealand and appears to be stable over time. GCA is uncommon in Maori, Pacific Islander and Asian ethnic groups.

Performance of a fast-track pathway for giant cell arteritis in Waikato, Aotearoa New Zealand.

AIMS: Giant cell arteritis (GCA) is the most common primary vasculitis in adults over 50 years of age. To facilitate early diagnosis and reduce harms from corticosteroids and temporal artery biopsies, fast-track pathways have been established. We review the benefits of the fast-track pathway set up in Waikato, Aotearoa New Zealand. METHODS: Patients were collected prospectively as part of the fast-track pathway from 2014 to 2022. Their records were then reviewed retrospectively to collect data on clinical features, investigations and treatment. RESULTS: There were 648 individual patients over the study period who had a colour Doppler ultrasound (CDUS) of the temporal arteries. There were 17 true positive CDUS, giving a sensitivity of 10.3% (95% confidence interval [CI] 6.3-15.5%) and specificity of 99.8% (95% CI 99.1-100%). Patients with GCA and a positive scan had significantly fewer steroids than those with GCA and a negative scan (p=0.0037). There were 376 patients discharged after a CDUS who did not have a diagnosis of GCA, resulting in reduced corticosteroid and temporal artery biopsy exposure. CONCLUSIONS: This is a real-life study that reflects the benefits of fast-track pathways in Aotearoa New Zealand to patients and healthcare systems. It also shows the effect of corticosteroids on positive CDUS, an important consideration when setting up an fast-track pathway.

Significance of combined anti-CCP antibodies and rheumatoid factor in a New Zealand cohort of patients with systemic sclerosis.

BACKGROUND: Systemic sclerosis (SSc) can present as an overlap syndrome with rheumatoid arthritis (SSc-RA overlap). OBJECTIVE: To evaluate the frequency of rheumatoid factor (RF) and anticyclic citrullinated peptide antibodies (anti-CCP) in our SSc cohort and their association with clinical features. METHODS: Data were gathered prospectively from the Waikato Hospital Systemic Sclerosis Clinics. Patients with SSc and SOS (systemic sclerosis overlap syndrome) underwent baseline auto-antibody profiling including RF and anti-CCP along with annual clinical review. RESULTS: Our cohort comprised of 132 patients (two had incomplete data); 115 (87.1%) were female. Out of 89 limited cutaneous SSc (lcSSc) patients, arthralgia, synovitis, contractures, tendon crepitus and erosions on imaging were found in three, 10, 31, five and nine patients, respectively. Within the 33 diffuse cutaneous SSc (dcSSc) patients, arthralgia, synovitis, contractures, tendon crepitus and erosion were found in 15, five, 27, five and one patient, respectively. In the 10 SOS patients, arthralgia, synovitis and contractures were found in six, three and two patients; none had tendon crepitus or erosions. RF positivity was found in 15.7%, 9% and 20% of patients with lcSSc, dcSSc and SOS, and anti-CCP positivity was found in 13.5%, 6.1% and 0% in lcSSc, dcSSc and SOS patients. A statistically significant relationship of double antibody positivity with arthralgia (P = 0.03) and erosions (P < 0.001) was found. Anti-CCP positivity association with erosions was significant at P = 0.007. CONCLUSION: Our study confirms that articular manifestations are common in SSc. Statistically significant associations of double antibody positivity with arthralgia and erosions were demonstrated. Significant association between anti-CCP antibody and erosions was also confirmed.