a weak trendP =0.052
When stratified according to age, the decreasing pattern of the prevalence of MRMP was observed with a weak trend significance ( P =0.052) as follows: 0–4 years, 95.1% (39 of 41); 5–9 years, 81.8% (36 of 44); 10–18 years, 77.8% (7 of 9) ( Fig. 1 ).