Objective: Progressive increases in the incidence rate of giant cell arteritis (GCA) have been observed in different geographic areas. The incidence of GCA in Lugo, Northwestern Spain, was previously considered low. Our aim was to analyze trends in incidence and clinical features of GCA in Lugo.
Methods: Retrospective study of biopsy proven GCA diagnosed from January 1, 1986 through December 31, 1995. The average annual incidence rate of GCA for population age > or = 50 years was analyzed at 5 year intervals from 1986 to 1995, inclusive. A comparative study of clinical features and laboratory findings of GCA in patients diagnosed 1991-1995 with those diagnosed 1986-1990 was performed.
Results: Forty-one and 52 Lugo residents were diagnosed with GCA in the 1986-1990 and 1991-1995 time periods, respectively. For each period the average annual incidence rate for population age > or = 50 years was 8.26 and 10.49/10(5), respectively. A lower frequency of classic features of GCA such as constitutional symptoms (67.3 vs 95.1%) and polymyalgia rheumatica (30.8 vs 51.2%) was observed in patients diagnosed 1991-1995. Other typical findings were less common than in the 1986-1990 period, namely, headache (82.7 vs 87.8%), abnormal examination of temporal artery (61.5 vs 70.7%), jaw claudication (36.5 vs 43.9%), and amaurosis fugax (9.6 vs 14.6%). There was a longer delay to diagnosis 1991-1995 than 1986-1990 (12.7 +/- 12.1 wks vs 8.9 +/- 6.2). Also, at the time of diagnosis, anemia, thrombocytosis, and elevated alkaline phosphatase were less frequently observed in the period 1991-1995.
Conclusion: In recent years, we observed a progressive increase in the incidence of GCA in our area. Such an increase correlates with lower frequency of classic manifestations of GCA.