How to model delayed count data due to time needed to form an event

Dear NONMEM Users, I'm dealing with some longitudinal count data (number of AEs observed in fixed time interval over certain time period). One feature with the data is the delay in PK/PD relationship because it takes time to develop the AE (i.e. there is lag time between the start of the AE formation process and the time you can observe the AE). The onset of the process of developing an AE is clearly PK dependent, but the exact time (or PK level) it onsets can never be observed. In addition, the exact time that the AE first appears is also not available, we only know the interval during which it first appears. What is a good approach to handle this kind of delay? Is there any published paper for similar data type? Many thanks in advance for you suggestions! Yaming Hang, Ph.D. Pharmacometrics Biogen Idec 14 Cambridge Center Cambridge, MA 02142 Office: 781-464-1741 Fax: 617-679-2804 Email: [email protected]<mailto:[email protected]>