How to calculate number of patients discontinue with the program?

Dears,
I’m looking for a way to aggregate number of patients discontinue with the program by checking if those patients do not come to facility for over 3 months (base on last due date).

How should I build the aggregate query or indicator in this case?

Thank you very much,

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Thai Chuong
HCMUT - Computer science and engineering Faculty

Website: http://thuytruc.net

YM/Skype : thaichuong159
Email: thaichuong159@gmail.com
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