SELECT
obs.value_text as 'Diagnosis',
count(obs.person_id) as 'Number of Patients',
person.gender,
person.birthdate,
e.encounter_datetime,
TIMESTAMPDIFF(YEAR, person.birthdate, CURDATE()) AS age
FROM openmrs.obs
inner join openmrs.person on obs.person_id = person.person_id
inner join encounter e on e.encounter_id = obs.encounter_id
where obs.concept_id='159393' and obs.voided=0 and person.voided=0
group by obs.value_text;