For instance, until a few years ago, regulatory agencies assessed the efficacy of antipsychotics on the basis of the improvement in psychotic symptoms. Today, cognitive and psychosocial outcome variables are also required. The parameters of response Many parameters may influence response and nonresponse. We will attempt to group them under a few headings. Definition

of end point and nonresponse Treatment response can be evaluated as a continuous measure, as a score Inhibitors,research,lifescience,medical on a rating scale, eg, the Hamilton Depression Scale (HAM-D), or as a category, such as improved, in remission, or relapsed. Often, different definitions have been used over time to characterize the outcome of treatments. This Inhibitors,research,lifescience,medical inconsistency was a problem in depression, for instance, and operational criteria have been proposed to define change points in the course of the illness.5 Niercnbcrg et al proposed that the following categorical outcomes are more clinically relevant than the mere improvement in depression rating scale scores: response (without remission), remission, nonresponse, partial response, relapse, recurrence, recovery, and, more recently, depressive breakthrough.6 Response to treatment supposes that the therapeutic targets that have been defined a priori – either symptoms or a syndrome – have been significantly modified by treatment. If Inhibitors,research,lifescience,medical rating scales are used, it is generally accepted that a change of less than 50% in the initial

score is significant. Bosutinib purchase Changes below that threshold will be considered as cases of nonresponse or insufficient response. Insufficient response or nonresponse does not always reflect the lack of efficacy

Inhibitors,research,lifescience,medical of the drug treatment that was chosen; it may be caused by other factors, including the patient’s constitution, concomitant somatic illness, pharmacogenetics (fast or slow drug metabolism), or environment (food or drug interactions). Placebo response and other biases The existence of a placebo response leads to the adoption Inhibitors,research,lifescience,medical of strict criteria for genuine response, hence the requirement of a 50% improvement in rating scale scores. Placebo response is linked to the patient’s emotional ties with the treatment, the clinician’s charisma, or the nursing care in hospital. Placebo response wears off or is less significant when the disorder is protracted, severe, or chronic. Independently of drug effect, several factors may influence response. The natural course of the disease else may lead toward spontaneous cure. For instance, 50% of patients with acute posttraumatic stress disorder (PTSD) will heal spontaneously within the first year of the traumatic event. Also, a physician following up a patient in a study will tend to see him or her as slightly improved with ongoing treatment, even in the absence of objective improvement. This “optimistic bias” might arise from the clinician’s sincere care for the patient, and also from the fact that success is easier to tolerate than failure.