Basic characteristics of the study population
Over 13 years, a total of 97, 252 patients visited the PAG department, and the total number of visits was 206,967. During the study period, the number of PAG patients that came in for a first visit increased gradually from 4,582 in 2006 to 11,876 in 2018 (Figure 1). Table 1 shows the characteristics of patients at first visit during the study period. The figures below ‘Follow-up times’ in the table refer to the number of patient visits. Patient ages ranged from 0 to 18 with a mean ± standard deviation (SD) of 6·3 ± 3·9 years; 51·7% of the participants were aged 0-6 years, 27·2% were aged 7-9 years, and 21·0% were aged 10-18 years. Over 94% of patients were from Zhejiang province; over half (55·2%) of the patients was from Hangzhou city, where the hospital is located. The average number of appointments per subsequent visited patient was 3·7.