Dear colleagues how does stata nbreg calculate adjusted incident rate ratios (IRR).Because from my example I know crude IRR=incident rate in (1999-2010)/Incident rate(2012-2019). How about adjusted incident rate ratio, for example in effect PCV10 impact on ipd adjusted for time.Is there a formula?: for <2 month the crude IRR=11.2/240.2. I am realy interested in knowing how adjusted one is calculated
Prevaccine era(1999-2010) Postvaccine era (2012-2019) Postvacine vs prevaccine era
n Incidence per 100,000 (95% CI) n Incidence per 100,000 (95% CI) IRR (95% CI) Adjusted IRR (95% CI)
IPD caused by any serotype
<2 months 43 240.2 (173.9-323.6) 2 11.2 (1.4-40.4) 0.04 (0.01-0.23) 0.08 (0.01-0.42)
<5 years 401 81.6 (73.8-89.9) 48 14.3 (10.5-19.0) 0.17 (0.06-0.43) 0.42 (0.17-1.07)
5-14 years 127 15.8 (13.2-18.8) 31 5.0 (3.4-7.1) 0.30 (0.11-0.80) 0.52 (0.19-1.40)
>=15 years 30 6.9 (4.7-9.9) 33 3.1 (2.1-4.3) 0.45 (0.12-1.66) 0.88 (0.24-3.26)