How to store answers

[xamelon]

Description

Form is a list of questions grouped together around specific problem.
Form is used to capture data from respondents (patients,practitioners, etc...).
When respondents fill out the form the answers should be stored in a database.
The format in which answers are stored is very important - that affects the usability and accessibility of that data.

FHIR already has an answer for the question - it has QuestionnaaireResponse resource in which
answers stored as a list of JSON objects.

Example:

[{:id "body-height"
 :text "Body Height"
 :value 180
 :unit "cm"},
{:id "body-weight"
 :text "Body Weight"
 :value 80
 :unit "kg"}]

In our current Aidbox Forms we have used a nested map with stripped values.

{:body-height 100
 :body-weigth 80}

Both variants has it's pros and cons. We need to test these options against our questions.

• how to simplify analysis, usage and data management (SQL, code)?
• how to handle nested and repeated questions
• should data be self-descriptive - to contain text of question and other Form DSL metadata?
• do we need separate resource for it or just use FHIR/QuestionnaireResponse?
• how to simplify data conversion to QuestionnaireResponse?

Problem

Find a solution that more appropriate according our questions

Use Cases

• user wants a way to query data easily and make analysis on it
• user wants to have QuestionnaireResponse as a result

Options

1. store items in a list
2. store items in a map

Decision matrix

Call for action

You can read more about options in next comments.
Please give your feedback - what do you think
or just vote for the comment with emoji or "up" button.

[xamelon]

1 Option: Store answers in a list

All answers stored in a list.
Every answer has an unique identificator - id which is referred to a question.

[{:id "body-height"
 :text "Body Height"
 :value 180
 :unit "cm"},
{:id "body-weight"
 :text "Body Weight"
 :value 80
 :unit "kg"}]

how to handle nested and repeated questions

Repeated values placed in the same list (like in QuestionnaaireResponse).
Repeated answers have the same id.

[{:id "blood-pressure-systolic"
 :text "Blood Pressure Systolic"
 :value 80
 :unit "mmHg"},
{:id "blood-pressure-systolic"
 :text "Blood Pressure Systolic"
 :value 85
 :unit "mmHg"}]

Nested values places under :item key in an answer

[{:id "blood-pressure"
 :text "Blood Pressure"
 :item [{:id "blood-pressure-systolic"
         :text "Systolic"
         :value 85
         :unit "mmHg"}]}]

how to query, anaslyse and manage data (SQL, code)?

To query data is not straightforward, because of array structure

select qr.id
from questionnaireresponse qr,
     jsonb_array_elements(resource->'item') item
where item->>'linkId' = 'body-weight'
and (item#>>'{answer,0,value,Quantity,value}')::int > 80

When answer is placed deeper in a tree then SQL is more complex. we need to traverse every level
with jsonb_array_elements.

select qr.*
from questionnaireresponse qr,
     jsonb_array_elements(resource->'item') item,
     jsonb_array_elements(item->'item') item2
where item->>'linkId' = 'blood-pressure'
and item2->>'linkId' = 'systolic' 
and (item2#>>'{answer,0,value,Quantity,value}')::int > 200

Analysis is also more difficult with this structure.

To get and update data in a code is also not a straightforward.
We need custom logic to traverse that arrays for searching address of a question.

(assoc-in qr (find-item-address qr :blood-pressure) new-value)
(get-in qr (find-item-address qr :blood-pressure))

This format requires more effort to work with

how to simplify data conversion to QuestionnaireResponse?

It's the same - don't need any special steps for conversion

[xamelon]

2 Option: Store answers in a map

All answers stored in a map.
Every answer has an unique identificator which is referred to a question.
This identifier - is a key in a map.

{:body-height {:text "Body Height"
               :value 180
               :unit "cm"}
 :body-weigth {:text "Body Weight"
               :value 80
               :unit "kg"}}

how to handle nested and repeated questions

Repeated values will be stored in a list under the map.

{:blood-pressure-systolic [{:text "Blood Pressure Systolic"
                            :value 80
                            :unit "mmHg"},
                           {:text "Blood Pressure Systolic"
                            :value 85
                            :unit "mmHg"}]}

nested values can be stored in a nested map under :item key

[{:blood-pressure {:text "Blood Pressure"
                   :item {:systolic {:text "Systolic"
                                     :value 85
                                     :unit "mmHg"}}}}]

how to query, anaslyse and manage data (SQL, code)?

select id from sdcdocument 
where (resource#> '{body-weight,value}')::int > 80

For more nested data - query is not become more complex

select * from sdcdocument 
where (resource#> '{blood-pressure,items,systolic,value}')::int > 200

In a code is simplest solution - we can use our build-in functions to get and update the data

(assoc-in qr [:blood-pressure :items :systolic] new-value)
(get-in qr [:blood-pressure :items :systolic])

But in this way we need to know full path to a data (don't just a id of an answer).

how to simplify data conversion to QuestionnaireResponse?

It requires the translation to QuestionnaireResponse.
Also there a need for additional effort to restore the questions order.