1
Level of evidence: Level III study, It is a case control study.
2
Design: Case- control study with 12 weeks' longitudinal follow-up to determine treatment response.
3
Methods: A retrospective case- control study was performed at 4 health maintenance organizations.
4
Methods: Case- control study, food trace-back and microbiologic investigations were promptly carried out.
5
One case- control study involving European patients with type 1 diabetes was included.
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Methods: A population based case- control study was conducted in 2 French agglomerations.
7
Study design, size, duration: A case- control study including three groups of patients.
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Methods: A case- control study was conducted based on Massachusetts birth certificate data.
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Patients and methods: A prospective case- control study in a district general hospital.
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Methods: A paired case- control study adjusted by age and gender was conducted.
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A retrospective case- control study was performed with two matched controls per case.
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A nested case- control study was subsequently performed to investigate potential risk factors.
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Methods: A population based case- control study was conducted among women in Michigan.
14
A case- control study was conducted to determine occupational risk factors for infection.
15
Design: A population-based, retrospective case- control study using the Houston Tuberculosis Initiative database.
16
To exclude non-specific changes, a control study with sham smoking was performed.