Calculating Drive Time Between Injury & Hospital in
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Calculating Drive Time Between Injury & Hospital in Spinal Cord Injury Research Using Online Navigation Tools. Jayson H. Shurgold. Background. ‘A world without paralysis after spinal cord injury’. Access to Care and Timing (ACT)

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Calculating drive time between injury hospital in

Calculating Drive Time Between Injury & Hospital in

Spinal Cord Injury Research Using Online Navigation Tools

Jayson H. Shurgold


Calculating drive time between injury hospital in

Background

‘A world without paralysis after spinal cord injury’

  • Access to Care and Timing (ACT)

  • Define the continuum of care experienced by individuals that suffer a traumatic spinal cord injury

  • Data is collected from 15 Canadian care centres that specialize in the acute care, treatment, and/or rehabilitation of patients with spinal cord injuries

  • The outcome is a mathematical model designed to predict the effect of specific scenarios, and the subsequent affect on patient flow and overall outcome

Injury

Acute Care

Rehab

Community


Calculating drive time between injury hospital in

Background

  • One hypotheses is that spinal cord injuries sustained closer to a specialized treatment centre results in more timely access to specialized care and overall better outcomes for the patient.

  • How do we define proximity?

  • From our data:

  • Time of injury

  • Time of admission to specialized hospital

  • First 3 digits of the postal code where the

  • injury occurred

  • Address of closest specialized hospital


Calculating drive time between injury hospital in

Background

Question 1:

Can we estimate proximity using

T admission - T injury

Injury at 2:00 PM

Admission at 6:00 PM

Proximity = 4 hours


Calculating drive time between injury hospital in

Background

Question 1:

Can we estimate proximity using

T admission - T injury

Injury at 2:00 PM

Admission at 6:00 PM

Proximity = 4 hours

Answer: Sometimes, but no.

In reality, ~34% of the observations are considered ‘indirect’. This means patients are admitted to a non-specialized centre prior to admission to a specialized centre.


Calculating drive time between injury hospital in

Background

Question 2:

Can we estimate proximity using built in functions?

- Geodist(latitude-1, longitude-1, latitude-2, longitude-2)

- Haverstine Formula

- SASHELP.zipcode


Calculating drive time between injury hospital in

Background

Question 2:

Can we estimate proximity using built in functions?

- Geodist(latitude-1, longitude-1, latitude-2, longitude-2)

- Haverstine Formula

- SASHELP.zipcode

Answer:

Not ideal.

If you happen to have the latitude and longitude of the incident and target in degrees, you can use the GeoDist function to calculate straight line distance.

Ignores roads and natural barriers


Calculating drive time between injury hospital in

Background

Question 3:

Can I just Google this?


Calculating drive time between injury hospital in

Background

Question 3:

Can I just Google this?

Answer:

You can, but it’s not recommended.

With large databases, doing this by hand takes a long time and is prone to error.


Calculating drive time between injury hospital in

Background

Question 4:

Is there any hope?


Calculating drive time between injury hospital in

SAS

Nav Systems


Calculating drive time between injury hospital in

Ash Roy & Yingbo Na

Canadian Institute for Health Information

Mike Zdeb

University of Albany School of Public Health


Calculating drive time between injury hospital in

Introduction to APIs

  • What is an API?

  • Application Programming Interface

  • ‘In most procedural languages, an API specifies a set of functions or routines that accomplish a specific task or are allowed to interact with a specific software component’

Graphic User Interface

Standard API output (XML)


Calculating drive time between injury hospital in

Introduction to APIs

Searching non-specific addresses:

Asking most navigation software to calculate directions between two FSAs or Postal Codes results in directions from ‘centroid to centroid’.

For example, the calculated distance between ‘V6B’ and ‘V6B 6P6’ is 0.4Km, centroid to centroid.

Forward Sortation Area (FSA):

V6B

Full Postal Code:

V6B 6P6


Calculating drive time between injury hospital in

Introduction to the dataset

Dataset: ACT_Raw

Data Dictionary


Calculating drive time between injury hospital in

Introduction to the dataset

Dataset: ACT_Raw

Concatenate the source and target location information into a single variable:

This is the start of determining the total number of unique queries.


Calculating drive time between injury hospital in

Data Manipulations

Dataset: PC (n=10)

Dataset: ACT_Dataset (n=12)

Remove duplicate postal code combinations:

There is no need to look up the same postal code twice. This will save time.

This step reduced the number of actual queries from 2101 to 994


Calculating drive time between injury hospital in

API Macro

Dataset: PC (n=10)

Dataset: Dist_Time (n=10)

Distance_Val (Kilometres)

Time_Val (Seconds)


Calculating drive time between injury hospital in

API Macro

Dataset: PC (n=10)

Dataset: Dist_Time (n=10)

Distance_Val (Kilometres)

Time_Val (Seconds)

Errors output as -2


Calculating drive time between injury hospital in

API Errors

Dataset: Dist_Time (n=10)

Dataset: Dist_Time (n=10)

Actual manual data entry for the ACT project is 18 / 994.


Calculating drive time between injury hospital in

Final Data

Dataset: Dist_Time (n=10)

Dataset: ACT_DriveTime (n=12)

Now we have an accurate, timely, and reproducible method to define

proximity based on two geographical locations*.

*until the technology changes


Calculating drive time between injury hospital in

Final Analysis

What if…

All patients were transported directly to a specialized health care centre, and how does this compare to the observed mean time to admission?

Assumptions

12 minute average response time

10 minute load delay

Restricted by speed limit

No traffic delay


Calculating drive time between injury hospital in

Final Analysis

What if…

All patients were transported directly to a specialized health care centre, and how does this compare to the observed mean time to admission?

Dataset: ACT_Simple

Dataset: ACT_Simple_Analysis


Calculating drive time between injury hospital in

Thank you for listening

  • Acknowledgements:

    • Mike Zdeb

    • University of Albany School of Public Health

    • http://www.sascommunity.org/wiki/Driving_Distances_and_Drive_Times_using_SAS_and_Google_Maps

    • Ash Roy & Yingbo Na

    • Canadian Institute fore Health Information

    • http://support.sas.com/resources/papers/proceedings12/091-2012.pdf

  • Special Thanks:

    • Suzanne Humphreys

    • Rick Hansen Institute

    • Argelio Santos

    • Rick Hansen Institute


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