incidence rate calculation

[manya92]

Hi all,

I am doing an incidence rate calculation for an analysis. The table that I have to produce looks like this :-

	ESRD Group
	Number of events	Percentages	Total Person years	Incidence rate	95% CI
Serious Infections
Hospitalization required
IV antibiotics required
Types of Serious Infections
Intestinal infectious diseases
Zoonotic bacterial diseases
Other bacterial diseases
Human Immunodeficiency Virus
Viral diseases accompanied by exanthema
Arthropod-borne viral diseases
Other diseases due to viruses & chlamydiae
Rickettsioses & other arthropod-borne diseases
Other spirochetal diseases
Helminthiases
Other infectious & parasitic diseases
Late effects of infectious & parasitic diseases
Opportunistic Infections

Now, I have made a macros to look for all the codes described in this table by different catergories of serious infections which looks like this : How can i compute incidence rate after this ?

First i have to find out patients who are at risk , compute person years = (period_stop - svcdate)/365 

then find patients who had an incidence of any of these infections

and then calculate incidence rate ..

how to do that ?

*STEP 1 ;

/*CALCUALTING THE NUMBER OF PATIENTS WITH THE APPLICABLE ENDPOINT (ONLY FIRST EVENT TO BE COUNTED) */

/*FLAG COMORBIDITIES  */

%macro incidence ;
	
	%do i = 1 %to 12 ;
	
		%let inf = %scan(int*zoo*othbact*hiv*vir*arth*chly*ricket*spiro*helminth*para*late, &i., *) ;
		
		/*intestinal infectious disease*/
		%let int = %str("001","002","003","004","005","006","007","008","009") ;
		
		/*zoonotic bacterial disease*/
		%let zoo = %str("020","021","022","023","024","025","026","027") ;
		
		/*other bacterial disease*/
		%let othbact = %str("030","031","032","033","034","035","036","037","038","039","040","041");
		
		/*hiv*/
		%let hiv = %str("042") ;
		
		/*viral diseases accompanied by exanthem*/
		%let vir = %str("050","051","052","053","054","055","056","057");
		
		/*arthropod-brone viral disease*/
		%let arth = %str("060","061","062","063","064","065","066");
		
		/*other diseases due to viruses and chlamydiae*/
		%let chly = %str("070","071","072","073","074","075","076","077","078","079");
		
		/*rickettsioses and otehr arthrpod-borne diseases*/
		%let ricket = %str("080","081","082","083","084","085","086","087","088");
		
		/*other spirochetal diseases*/
		%let spiro = %str("100","101","102","103","104");
	
		/*helminthiases*/
		%let helminth = %str("120","121","123","124","125","126","127","128","129");
		
		/*other infectious and parasitic diseases*/
		%let para = %str("130","131","132","133","134","135","136");
		
		/*late effects of infectious and parasitic diseases*/
		%let late = %str("137","138","139");
		
	%end ;
		
	/*FLAG PATIENT WITH THE ABOVE MENTIONED COMORBIDITIES ATFTER INDEX_DATE BUT BEFORE PERIOD_STOP*/;
	data _04_postindex_&inf. ;
		set derived._01_ic_of_i2;
		&inf. =1 ;
		where (code in:(&&&inf.)) and (index_date le svcdate le period_stop) ;
	run ;
	
	proc sort data = _04_postindex_&inf. out= _04_postindex_&inf._s ;
		by enrolid index_date svcdate ;
	run ;
	
	data _04_postindex2;
		set _04_postindex_&inf._s ;
		by enrolid svcdate ;
		format first_svcdate_&inf. mmddyy10. ;
		if first.enrolid then first_svcdate_&inf. = svcdate ;
	run ;
	
	/*FLAG PATIENTS WITH THE ABOVE MENTIONED COMORBIDITES BEFORE THE INDEX_DATE */
	
%mend incidence;
%incidence;

[StatDave]

I'm not sure what data manipulations you need, but once you have a data set of the relevant people including the number of incidents and their person-time, you can estimate the incidence rate using PROC GENMOD as discussed and illustrated in this note.