9.8.2 Prognosis Questions

Prognosis Questions: Critically Appraise Cohort Studies as Used to Address Prognostic Questions

Cohort studies are an essential tool to evaluate prognosis, i.e., the probability of an individual developing a particular outcome given a specific exposure or condition. These studies involve following up with a group of individuals with a particular characteristic or exposure over time and observing the occurrence of a particular outcome of interest. However, the validity of a cohort study depends on various factors that need to be critically appraised.

The following are some of the key considerations when critically appraising a cohort study for prognostic questions:

• Study design: Cohort studies are the most appropriate design for answering prognostic questions. However, it is essential to check if the study design is appropriate for the research question.

• Study population: The study population should be representative of the target population, and it is essential to evaluate if the inclusion and exclusion criteria are well defined.

• Exposure: The exposure should be clearly defined, and the assessment of exposure should be objective and valid.

• Outcome: The outcome should be clearly defined, and the assessment of the outcome should be objective and valid.

• Follow-up: The follow-up period should be sufficiently long to allow the outcome to occur. The follow-up rate should be high enough to avoid bias.

• Confounding: Confounding factors should be identified and controlled for in the analysis.

• Statistical analysis: The statistical analysis should be appropriate for the research question, and the results should be presented with measures of precision (e.g., confidence intervals).

• Generalizability: It is essential to evaluate if the results are applicable to the target population.

• Bias: Bias can occur due to various factors such as selection bias, measurement bias, and confounding. It is essential to evaluate if the study has adequately addressed potential sources of bias.

References:

1. Moons, K. G., Royston, P., Vergouwe, Y., Grobbee, D. E., & Altman, D. G. (2019). Prognosis and prognostic research: what, why, and how? Bmj, 358, j3885.