Case Control Study - Does the Case/Control have to be an outcome?

Case Control Study - Does the Case/Control have to be an outcome?

by | JUDITH MARGARET BURCHARDT -
Number of replies: 6

Hello,

I was thoroughly confused by this website  https://www.gov.uk/guidance/case-control-study-comparative-studies which describes a paper (details below) where they call cases post-operative bariatric surgery patients who have telemedicine technology and controls post-operative bariatric surgery patiints who do not and then looks at how well they attend for follow up.

I had thought that case/control status had to be an outcome, and that aim of a case control study was to examine the exposure. In this study it seems to me that the case/control status is an exposure and they are examining an outcome. I would describe this as an observational cohort study. What do others think?


Thank you


Judith 



Example: Can telemedicine help with post-bariatric surgery care? A case-control design

In 2019, Wang and colleagues published a paper entitled Exploring the Effects of Telemedicine on Bariatric Surgery Follow-up: a Matched Case Control Study.

The study showed that people who go through bariatric surgery have better outcomes if they attend their follow-up appointments after surgery in comparison to those who do not. However, attending appointments can be challenging for people who live in remote areas. In Ontario, Canada, telemedicine suites were set up to enable healthcare provider-patient videoconferencing.

The researchers used a matched case-control study to investigate if telemedicine videoconferencing can support post-surgery appointment attendance rates in people who live further away from the hospital sites. They used the existing data from the bariatric surgery hospital programme to identify eligible patients.

All patients attending the bariatric surgery were offered telemedicine services. The cases were the participants who used telemedicine services; they were compared to those who did not (the controls).

Cases and controls were matched on various characteristics, specifically:

  • gender
  • age
  • time since bariatric surgery
  • body mass index (BMI)
  • travel distance from the hospital site

Researchers measured:

  • the percentage of appointments attended
  • rates of dropout
  • pre-and post-surgery weight and BMI
  • various physical and psychological outcomes

They also calculated rurality index to classify patients into urban, non-urban and rural areas. These variables were used to compare cases (those who used telemedicine) and controls (those who did not).

During the study period, they identified that 487 patients of 1,262 who received bariatric surgery used telemedicine services. Of those, 192 agreed to participate in the study.

They found that patients who used telemedicine did as well as patients who attended in person, both in terms of appointment attendance rates and in terms of physical and psychological outcomes.

Moreover, the researchers found that the cases (telemedicine users) came from more rural areas than the controls. The authors argued that this demonstrated that telemedicine can help overcome the known challenges for patients in more rural areas to attend appointments.

Randomising patients to telemedicine or withdrawing the telemedicine would be difficult, undesirable and possibly unethical. Case-control was a good alternative to assess the potential impact on patient outcomes in a service that is already up and running.


In reply to | JUDITH MARGARET BURCHARDT

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | FLORIAN MODLER -
Hi Judith,
I agree with you that this study is incorrectly labeled as a case-control study. I cannot access the fulltext, but it looks like a restrospective (observational) cohort study. The only thing it seems to have in common with a c/c study is that both the exposure (tele y/n) and the outcomes had happened in the past.
Cheers,
Florian
In reply to | FLORIAN MODLER

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | JUDITH MARGARET BURCHARDT -

Thank you Florian and Nico,

I was a bit nonplussed, because in general I find gov.uk sites reliable. Thank you for your help.


Best wishes

Judith 

In reply to | JUDITH MARGARET BURCHARDT

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | ANDRES NICOLAS REARTE -
Hi Judith,
That is an exciting question.
I agree with Florian; it seems this was a historical cohort study. They included those exposed and unexposed to telemedicine, and then they followed them to assess adherence, etc.
It's not clear to me how they sampled the "controls" (unexposed to telemedicine) to see if the weights in both groups were proportional (They included less than 50% of those exposed to telemedicine, but there is no data on unexposed).
All the best
Nico
In reply to | JUDITH MARGARET BURCHARDT

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | Monica Mtei -

Hi Judith,


This is unlikely to be a case-control because they are inquiring about the outcome (follow-up) among exposed(those using telemedicine)  and unexposed (those who do not) which is a typical characteristic of a historical cohort. Also, the method of selection of controls is not well elaborated.

Best wishes,

Monica

In reply to | JUDITH MARGARET BURCHARDT

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | Sujit Rathod -
Hi Judith - consider writing to the corresponding author. I agree with the others that this appears to be a historic cohort. This is a situation where a study flowchart would be helpful.

Also - it seems that the researchers got consent for the telemedicine patients, but what about from the non-telemedicine patients??
In reply to | Sujit Rathod

Re: Case Control Study - Does the Case/Control have to be an outcome?

by | JUDITH MARGARET BURCHARDT -
Thank you Monica and Sujit,

I am reassured that I do understand the basics!

Best wishes

Judith
Accessibility

Background Colour

Font Face

Font Size

1

Text Colour