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# Continuous Enrollment for 18 months from 2015 to 2016

Hello,

I am trying to figure what is the bast way to determine the members that have a continuous enollement from 01/25/2017 for 18 months.  I used the lag function and was able to calculate their start of the coverage and the term of the coverage.

The orginal table contains this data:

Patid Drug_Cov Drug_term

1        01Jan2014  31Dec2014

1         01Jan2015  31Dec2015

1         01Jan2016   31Dec2016

1         01Jan2017   01Jan3000

2        01Jan2015  31Dec2014

2         01Jan2016  31Dec2015

2         01Jan201   01Jan3000

3         01Feb2015  11May2015

3         12May2015   31Oct2015

I used the lag function to determine the continuous the drug coverage and drug term date:

With the lag function, this is the table:

Patid    Drug_Cov  Drug_Term

1  01Jan2014 01Jan3000

2   01Jan2015  01Jan3000

3   01Feb2015   31Oct2015

How do I now determine the members that has an 18 months continuous enrollent from today date?

Accepted Solutions
Solution
‎01-25-2017 02:38 PM
Posts: 1,337

## Re: Continuous Enrollment for 18 months from 2015 to 2016

Posted in reply to ssitharath0420

What do your mean by "18 months continuous enrollent from today date"?  Currently active with a starting data at least 18 months ago?  That's what I assume.  The following program should do (I had to correct two of your data entries?):

``````data have;
input Patid Drug_Cov :date9. Drug_term :date9. ;
format drug_cov drug_term \$date9.;
datalines;
1        01Jan2014  31Dec2014
1        01Jan2015  31Dec2015
1        01Jan2016   31Dec2016
1        01Jan2017  01Jan3000
2        01Jan2015  31Dec2014
2        01Jan2015  31Dec2015    /* change 01jan2016 to 01jan2015*/
2        01Jan2016  01Jan3000    /* change 01jan201  to 01jan2016*/
3        01Feb2015  11May2015
3        12May2015  31Oct2015
run;

data spells (drop=next_cov first_cov);
set have (keep=patid);
by patid ;
retain first_cov;
merge have
have (firstobs=2 keep=drug_cov rename=(drug_cov=next_cov));

/* if this is beginning-of-spell, set first_cov value*/
if first.patid or drug_cov-1 > lag(drug_term) then first_cov=drug_cov;

/* See if at end-of-spell and whether its date range qualifies*/
if last.patid   or next_cov > drug_term + 1 then do;
drug_cov=first_cov;
if drug_term>=today() and intck('month',drug_cov,today()+1,'continuous')>=18 then output;
end;
run;``````

The "continuous" argument of the INTCK function says not to count calendar month boudaries, but rather use the actual date of drug_cov vs today as a way to count months.

All Replies
Solution
‎01-25-2017 02:38 PM
Posts: 1,337

## Re: Continuous Enrollment for 18 months from 2015 to 2016

Posted in reply to ssitharath0420

What do your mean by "18 months continuous enrollent from today date"?  Currently active with a starting data at least 18 months ago?  That's what I assume.  The following program should do (I had to correct two of your data entries?):

``````data have;
input Patid Drug_Cov :date9. Drug_term :date9. ;
format drug_cov drug_term \$date9.;
datalines;
1        01Jan2014  31Dec2014
1        01Jan2015  31Dec2015
1        01Jan2016   31Dec2016
1        01Jan2017  01Jan3000
2        01Jan2015  31Dec2014
2        01Jan2015  31Dec2015    /* change 01jan2016 to 01jan2015*/
2        01Jan2016  01Jan3000    /* change 01jan201  to 01jan2016*/
3        01Feb2015  11May2015
3        12May2015  31Oct2015
run;

data spells (drop=next_cov first_cov);
set have (keep=patid);
by patid ;
retain first_cov;
merge have
have (firstobs=2 keep=drug_cov rename=(drug_cov=next_cov));

/* if this is beginning-of-spell, set first_cov value*/
if first.patid or drug_cov-1 > lag(drug_term) then first_cov=drug_cov;

/* See if at end-of-spell and whether its date range qualifies*/
if last.patid   or next_cov > drug_term + 1 then do;
drug_cov=first_cov;
if drug_term>=today() and intck('month',drug_cov,today()+1,'continuous')>=18 then output;
end;
run;``````

The "continuous" argument of the INTCK function says not to count calendar month boudaries, but rather use the actual date of drug_cov vs today as a way to count months.

Contributor
Posts: 21

## Re: Continuous Enrollment for 18 months from 2015 to 2016

Thank you so much! It worked!

Contributor
Posts: 47

## Re: Continuous Enrollment for 18 months from 2015 to 2016

Posted in reply to ssitharath0420

Hi there, how did you create your output dataset using lag and retain function to get continous enrollment ?

☑ This topic is solved.

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