Table 1.
Risks of a child with autism having been diagnosed within a diagnostic cluster relative to all children diagnosed with autism and Population Attributable Fractions for diagnostic clusters
| Yeara | Relative risk, unadjusted clusters |
Relative risk, adjusted clustersb |
Population Attributable Fraction, unadjusted clusters |
Population Attributable Fraction, adjusted clustersb |
|---|---|---|---|---|
| 1998 | 9.83 | 7.49 | 5.32 | 5.14 |
| 1999 | 4.98 | 3.71 | 3.68 | 2.52 |
| 2000 | 5.03 | 4.02 | 3.4 | 2.55 |
| 2001 | 5.13 | 4.34 | 3.62 | 2.7 |
| 2002 | 4.33 | 4.56 | 3.12 | 3.03 |
| 2003 | 4.37 | 3.68 | 3.17 | 2.59 |
| 2004 | 5.29 | 4.43 | 4.07 | 2.97 |
| 2005 | 4.24 | 3.81 | 2.93 | 2.48 |
a
No significant cluster was detected in 1997.
b
Adjusted for: male sex, Medi-Cal insurance status, preterm birth, low birth weight status, mean parental age, mean parental education, and race/ethnicity