Help identifying the first positive hospital admission, re-admissions and ED presentations prior to first admission.

[Minda Sarna]

Hello,
I have a dataset with hospital and emergency data appended together. I also have virus testing data (positive / negative) for influenza virus. I'd like some help identifying a) the first admission for a child that is influenza positive; b) the number of re-admissions in a 14-day period after the discharge date of this first (positive) admission; c) the number of emergency presentations prior to this first admission.

Here is some sample data:

child_id	admdate_H	admdate_E	dischargedate	influenza
1	1-Sep-19	.	3-Sep-19	.
2	4-Sep-14	.	30-Dec-14	.
2	10-Feb-15	.	10-Feb-15	.
2	17-Apr-15	.	19-Apr-15	.
2	1-Jun-15	.	3-Jun-15	.
2	3-Aug-15	.	5-Aug-15	.
2	26-Aug-15	.	1-Sep-15	.
2	2-Sep-15	.	6-Sep-15	.
2	12-Oct-15	.	13-Oct-15	.
2	20-Apr-16	.	21-Apr-16	1
2	24-Apr-16	.	3-May-16	.
2	2-Feb-17	.	7-Feb-17	.
2	26-Feb-18	.	1-Mar-18	.
2	1-Jul-18	.	7-Jul-18	.
2	25-Sep-19	.	27-Sep-19	0
2	2-Aug-21	.	2-Aug-21	.
2	24-Jan-22	.	12-Feb-22	.
3	.	19-Jul-17	.	.
3	.	20-Jul-17	.	.
3	21-Jul-17	.	22-Jul-17	.
3	23-Jul-18	.	25-Jul-18	1
3	27-Oct-20	.	27-Oct-20	.

Missing in the influenza column = not tested, which we can treat as 0=negative. 1=positive.

Many thanks for your help.
best wishes
Minda Sarna

[Carlo Lazzaro]

Minda:
please provide an excerpt of your dataset via -dataex-. Thanks.