Prospective single-arm cohort study [Neurosurgery Wiki]

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====== Prospective single-arm cohort study ======

A prospective [[single-arm]] [[cohort study]] is a type of [[observational]] clinical [[study]] with the following characteristics:

✅ Definition:

A prospective single-arm cohort study follows a group of participants over time without a comparison (control) group, where all participants receive the same treatment or intervention, and outcomes are measured forward in time from the point of enrollment.

🧠 Key Components:

[[Prospective]]: Data is collected forward from a defined starting point (e.g., initiation of treatment).

[[Single-arm]]: There is only one group in the study; no randomization or control/placebo group.

[[Cohort]]: A defined group of individuals with shared characteristics (e.g., disease, treatment) is followed over time.

Study [[purpose]]: Often used to assess feasibility, safety, or efficacy of an intervention in early-phase clinical research.

📘 Example Use Case:

Evaluating the safety and outcomes of a new surgical technique in 100 patients with Chiari I malformation, all treated the same way and followed for 12 months
((Henry LC, McDowell MM, Stephenson TL, Crittenden JB, Byrd AL, Fernández-de Thomas RJ, Chang YF, Nowicki KW, Mantena R, Strick PL, Friedlander RM. Predecompression and postdecompression cognitive and affective changes in Chiari malformation type I. J Neurosurg. 2025 Feb 21;143(1):4-12. doi: 10.3171/2024.8.JNS241363. PMID: 39983117.))

⚠️ Limitations:

No control group limits ability to attribute [[causality]].

Susceptible to [[bias]] (e.g., selection bias, confounding).

Results are [[hypothesis-generating]], not confirmatory.