Exposure Episode Offset Credit Tool

Description

Shift supplied half-open record episodes and remove explicitly supplied overlap credit.

Drug-utilization research often reconstructs exposure from dispensing dates, supplied coverage windows, coding systems, and eligibility records. Day counts depend on endpoint and stockpiling policies. Observed records, assumed exposure, and actual medication consumption are different quantities.

Shift supplied half-open record episodes and remove explicitly supplied overlap credit.

When to use this tool

Use Exposure Episode Offset Credit when you need this explicit exposure-record, date-window, reporting-base, or evidence-support calculation.

How to use the tool and how it works

Enter startDay, endDay, suppliedOffsetDays, creditedOverlapDays. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read shiftedStart, shiftedEnd, creditedDays. Use the output convention below.

Require endDay>=startDay and integer creditedOverlapDays between zero and endDay-startDay. Add suppliedOffsetDays to both endpoints and return creditedDays=endDay-startDay-creditedOverlapDays.^[1]

Input field	Meaning and units	Accepted input
startDay	Start Day	Required. Safe integer.
endDay	End Day	Required. Safe integer.
suppliedOffsetDays	Supplied Offset Days	Required. Safe integer.
creditedOverlapDays	Credited Overlap Days	Required. Safe integer; minimum 0.

Output field	Interpretation	Returned shape
shiftedStart	Shifted Start	Required. Safe integer.
shiftedEnd	Shifted End	Required. Safe integer.
creditedDays	Endpoint difference minus credited overlap, without an inclusive-day addition.	Required. Safe integer.

json

{
  "input": {
    "startDay": 10,
    "endDay": 30,
    "suppliedOffsetDays": 2,
    "creditedOverlapDays": 5
  },
  "output": {
    "shiftedStart": 12,
    "shiftedEnd": 32,
    "creditedDays": 15
  }
}

Limitations and assumptions

The duration is an endpoint difference without an inclusive-day addition. Shifting the episode does not change creditedDays or verify an exposure episode's biological or study eligibility meaning.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Signed zero is exported as zero.

Alternative or Complementary methods

Choose a documented exposure and eligibility definition for the study before combining records. Verify the coding version, observation windows, endpoint convention, and the evidence for assumptions about carried supply.

References

Calculation and input contract: pharmacoepidemiology/exposure-episode-offset-credit — tool.io

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