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Table 3 Multilevel zero-inflated negative binomial regression models for DMFT score in children aged 12 years in China in 2005 and 2015 surveys

From: Trend on dental caries status and its risk indicators in children aged 12 years in China: a multilevel analysis based on the repeated national cross-sectional surveys in 2005 and 2015

  2005 data 2015 data 2005 and 2015 combined
PRR (95% CI) p value PRR (95% CI) p value PRR (95% CI) p value
Level-1 indicators
Sex
Female (vs. Male) 1.19(1.09-1.30) 0.0001 1.23(1.17-1.29) <0.0001 1.22(1.17-1.27) <0.0001
Ethnicity
Other (vs. Han) 1.11(0.96-1.28) 0.15 0.96(0.88-1.04) 0.30 0.99(0.92-1.07) 0.78
Location of residence
Rural (vs. Urban) 1.06(0.96-1.16) 0.24 1.01(0.96-1.07) 0.59 1.03(0.99-1.08) 0.14
Only child
Yes (vs. No) 0.95(0.86-1.05) 0.29 0.96(0.92-1.01) 0.11 0.98(0.93-1.02) 0.33
Parental highest education attainment (vs. Junior high school or below)
High school 1.05(0.92-1.19) 0.47 1.02(0.95-1.11) 0.54 1.04(0.97-1.11) 0.29
Tertiary or bachelor degree or above 1.11(0.94-1.30) 0.22 1.02(0.93-1.12) 0.63 1.04(0.96-1.13) 0.30
Unknown or orphan 1.06(0.85-1.31) 0.62 1.04(0.95-1.15) 0.39 1.05(0.96-1.15) 0.27
Toothbrushing frequency
Twice or more per day (vs. Once a day or less) 0.92(0.83-1.01) 0.087 1.02(0.98-1.06) 0.40 1.01(0.97-1.06) 0.60
Use of dental floss
Yes (vs. No or do not know) 0.95(0.80-1.12) 0.53 1.06(0.99-1.14) 0.098 1.05(0.98-1.12) 0.15
Frequency of toothache within the past 12 months (vs. Never)
Often 1.40(1.15-1.70) 0.0008 1.45(1.30-1.62) <0.0001 1.44(1.31-1.59) <0.0001
Occasionally 1.25(1.12-1.39) <0.0001 1.28(1.21-1.36) <0.0001 1.27(1.21-1.33) <0.0001
Can't remember 1.09(0.95-1.25) 0.21 1.08(1.00-1.18) 0.063 1.08(1.00-1.16) 0.037
Time of last dental visit (vs. Never)
Within 6 months 1.23(1.07-1.43) 0.0047 1.43(1.33-1.52) <0.0001 1.40(1.32-1.49) <0.0001
Within 6 to 12 months 1.13(0.98-1.31) 0.095 1.25(1.17-1.34) <0.0001 1.23(1.16-1.31) <0.0001
More than 12 months 1.32(1.20-1.46) <0.0001 1.17(1.10-1.24) <0.0001 1.21(1.15-1.27) <0.0001
Dental fluorosis
Yes (vs. No) 1.08(0.95-1.22) 0.25 0.95(0.89-1.01) 0.11 0.98(0.92-1.03) 0.37
Frequency of sweet snack intake (vs. Occasionally/ never)
Less than 2 times per week 0.92(0.81-1.05) 0.23 1.04(0.97-1.11) 0.29 1.00(0.93-1.07) 0.91
2 to 6 times per week 0.96(0.83-1.11) 0.58 1.09(1.02-1.17) 0.0073 1.03(0.96-1.10) 0.41
More than 6 times per week 0.93(0.82-1.04) 0.21 1.13(1.06-1.21) <0.0001 1.06(0.99-1.13) 0.10
Year of survey
2015 (vs. 2005) .. .. .. .. 1.30(1.23-1.37) <0.0001
Level-2 indicators
Economic development (vs. GDP per capita, quartile 1)
GDP per capita, , quartile 2 0.98(0.75-1.29) 0.90 1.08(0.86-1.35) 0.53 1.01(0.90-1.14) 0.85
GDP per capita, , quartile 3 1.21(0.90-1.62) 0.21 0.96(0.76-1.20) 0.71 0.96(0.86-1.08) 0.52
GDP per capita, , quartile 4 1.13(0.85-1.51) 0.40 1.10(0.87-1.38) 0.44 0.88(0.77-1.01) 0.068
Region (vs. East China)
North China 0.86(0.65-1.13) 0.27 0.93(0.73-1.19) 0.57 0.97(0.77-1.22) 0.80
Northeast China 1.15(0.84-1.57) 0.39 1.50(1.09-2.07) 0.014 1.35(1.03-1.77) 0.031
Middlesouth (Central) China 1.13(0.86-1.50) 0.38 1.18(0.92-1.52) 0.18 1.11(0.89-1.38) 0.37
Southwest China 1.27(0.91-1.78) 0.16 1.40(1.07-1.83) 0.013 1.26(0.99-1.59) 0.06
Northwest China 0.94(0.68-1.29) 0.69 1.05(0.79-1.39) 0.73 0.94(0.74-1.20) 0.64
  1. PRR = Prevalence rate ratio
  2. CI = Confidence interval