The phrase "an unmatched case" is correct and usable in written English.
It can be used to refer to a situation or instance that does not have a corresponding or equivalent counterpart.
Example: "In our analysis, we found an unmatched case that required further investigation to understand its implications."
Alternatives: "a unique instance" or "an unpaired example."
Specifically, Freer et al.[6], in an unmatched case control study in Mulago Hospital, Kampala of 61 EMF patients and 120 controls, show that EMF patients were significantly more likely than controls to have Rwanda/Burundi ethnic origins (P = 0.008), be peasants (P<0.001), and to come from defined geographical locations (P = 0.003).
The study design was an unmatched case control which included 844 women (408 cases and 436 controls).
We therefore conducted an unmatched case control study to identify the factors associated with obstetrics fistula among patients attending selected hospitals in Kenya.
Odds ratios (ORs) were calculated using the online software "calculator for confidence intervals of OR in an unmatched case control study" available at http://www.hutchon.net/ConfidOR.htm.net/ConfidOR.htm
This study used an unmatched case control design and was conducted among clients who were provider initiated for HIV testing in eight OPDs of four public health facilities in Jimma town.
Assuming an unmatched case control design with alpha = 0.05 and beta = 0.80, post-hoc power analysis was performed to determine the minimum detectable relative risk detectable with the given sample size [ 24].
We conducted an unmatched case-control study of 133 cases of KD and 312 controls collected between January 2002 and April 2005.
We assumed an unmatched case-control design (EPIC 1∶3.4, MeSyBePo 1∶3.7, Leipzig 1∶0.94), a population risk of 0.06 for T2DM and considered a two-sided p-value of 0.05.
Due to the relative infrequence of symptomatic thromboembolic events while using pharmacological agents as prophylaxis, an unmatched case-control study design was employed.
With these principles in mind, we first depict the causal structure of an unmatched case-control study, assuming only one confounder.
We identified risk factors for Buruli ulcer (BU) in Benin in an unmatched case-control study at the Centre Sanitaire et Nutritionnel Gbemoten in southern Benin.
