Most accurate way to count months between two date variables?

[accintron]

I've used the following code to calculate months between two date variables, however, I feel like it's not as accurate as I'd like it to be... 

data readms_dist2;
set readms_dist2;

Months_btwn_adms=intck('month', PRV_DC_DT, ADM_DT);
Weeks_btwn_adms=intck('week', PRV_DC_DT, ADM_DT);
Days_btwn_adms=intck('day', PRV_DC_DT, ADM_DT);

run;

From my understanidng, the intck month function just counts if the date has "crossed" into the next month -

So if had a PRV_DC_DT was january 1 2020 and the ADM_DT was january 30 2020, then the function would return 0.

but if PRV_DC_DT was january 30 2020 and ADM_DT was february 1 2020 then the function would return 1. This is correct right? Well, that's not very accurate in calculating how many months between two dates, so what's my best option?

Thanks!

[novinosrin]

Use 'C' for continuous

Months_btwn_adms=intck('month', PRV_DC_DT, ADM_DT,'c');

[accintron]

Thank you! 

[Reeza]

Look at the fourth parameter in the INTCK() function.

However, a month does not a standard definition, ie it could be 28 days or 31 days which can be a 10% difference there. It depends on what you need. You can use # of days or some other measure but it depends on what you're calculating and what the rules are.

[accintron]

Yes, ok, I see that's what the other post did with the 'c' for continuous. This is good enough for my purposes 🙂

[Reeza]

This is the reason the standards were set at 30/90/180 re-admission rates though 🙂

[accintron]

Makes sense. Is there a way to count by 30 day intervals? Can you use that as the fourth parameter?

[novinosrin]

Hi @accintron  Not quite using the fourth argument. But you can use an Interval Multiplier to Create a Custom Interval.

For example day30 as the interval in your case

Months_btwn_adms=intck('day30', PRV_DC_DT, ADM_DT);

[accintron]

Ah ok! This is great. thanks so much. I'll check out both!

[novinosrin · Accepted solution]

IMHO, you would still need to test carefully with "C" and without "C"

Months_btwn_adms=intck('day30', PRV_DC_DT, ADM_DT,"c");

It seems quite likely you would need a 'C' for your custom interval too 

[accintron]

Ok, thank you for this advice. I will try out all three! 🙂