Efficacy assessed in follow-ups of clinical trials: methodological conundrum

Increasingly, we see papers describing the long-term follow-up results of randomised clinical trials. Sometimes, like the article by Rantalaiho and colleagues in the previous issue of Arthritis Research & Therapy, the follow-up extends to more than 10 years. It is not uncommon that authors of such articles describe their results as a comparison of the original treatment groups in the original randomised clinical trial. Methodologically, such a comparison is fallible for several reasons. In this editorial, two important sources of bias that may jeopardise the results of such follow-up studies are discussed: confounding by indication and confounding by trial completion.     

Application of stains in clinical microbiology

Stains have been used for diagnosing infectious diseases since the late 1800s. The Gram stain remains the most commonly used stain because it detects and differentiates a wide range of pathogens. The next most commonly used diagnostic technique is acid-fast staining that is used primarily to detect Mycobacterium tuberculosis and other severe infections. Many infectious agents grow slowly on culture media or may not grow at all; stains may be the only method to detect these organisms in clinical specimens. In the hands of experienced clinical microscopists, stains provide rapid and cost-effective information for preliminary diagnosis of infectious diseases. A review of the most common staining methods used in the clinical microbiology laboratory is presented here.