Be skeptical about unexpected large apparent treatment effects: the case of an MRC AML12 randomization

The preliminary results of the twelfth Medical Research Council acute myeloid leukemia trial show no evidence of a survival advantage for five courses of therapy compared to four courses in a randomized comparison involving 1078 patients (hazard ratio 1.09, 95% confidence interval [CI] 0.87-1.37, p=0.4). However, the data presented to the independent data monitoring and ethics committee (DMEC) at both its reviews in 1998 suggested large benefits for the additional course with hazard ratios of 0.47 and 0.55 (95% CIs 0.29-0.77 and 0.38-0.80, p=0.003 and p=0.002, respectively). Despite these highly significant findings, the DMEC did not recommend closure of the randomization, a decision vindicated by the subsequent reversion to a null result. The main reason for not closing the randomization was that the treatment effects observed in 1998 (53% and 45% reductions in the odds of death) were considered too large to be clinically plausible, despite the p-values associated with them. Investigations have not identified any clinical explanations, such as different types of patients in the early and later parts of the trial, to explain the loss of benefit as the trial progressed. Thus, the most likely current explanation for the large benefit observed early on is the play of chance. Lessons to be learned from this example are that: fixed stopping rules based on some predetermined p-value should not be used and the decision to close a randomization or not should take account of other factors such as the medical plausibility of the magnitude of the treatment effect; chance effects do occur and happen more frequently than many clinicians realize; it is important that DMEC members are experienced in the interpretation of clinical trial evidence and aware of the dangers of early stopping without wholly convincing evidence.     

Personalized mailed feedback for college drinking prevention: a randomized clinical trial

The current study was designed to evaluate the efficacy of a mailed feedback and tips intervention as a universal prevention strategy for college drinking. Participants (N = 1,488) were randomly assigned to feedback or assessment-only control conditions. Results indicated that the mailed feedback intervention had a preventive effect on drinking rates overall, with participants in the feedback condition consuming less alcohol at follow-up in comparison with controls. In addition, abstainers in the feedback condition were twice as likely to remain abstinent from alcohol at follow-up in comparison with control participants (odds ratio = 2.02), and feedback participants were significantly more likely to refrain from heavy episodic drinking (odds ratio = 1.43). Neither gender nor severity of baseline drinking moderated the efficacy of the intervention in these analyses, but more conservative analyses utilizing last-observation carryforward suggested women and abstainers benefited more from this prevention approach. Protective behaviors mediated intervention efficacy, with participants who received the intervention being more likely to use strategies such as setting limits and alternating alcohol with nonalcoholic beverages. Implications of these findings for universal prevention of college drinking are discussed.     

The subcellular localisation of trypanosome RRP6 and its association with the exosome

The exosome, a complex of 3'-exoribonucleases and associated proteins, is involved in the degradation of eukaryotic mRNAs in the cytoplasm, and has RNA processing and quality control functions in the nucleus. In yeast, the nuclear exosome differs from the cytoplasmic one in that it contains an additional non-essential component, Rrp6p. In contrast, a small proportion of human RRP6 has been shown to localise to the cytoplasm as well. When we purified the Trypanosoma brucei exosome from cytosolic extracts we found RRP6, apparently in stoichiometric amounts. We here confirm that RRP6 is in the trypanosome cytoplasm and nucleus. The level of RRP6 was unaffected by depletion of core exosome subunits by RNA interference and over-expression of tagged RRP6 was possible, indicating that RRP6 can be present independent of exosome association.     

Truth-telling in discussing prognosis in advanced life-limiting illnesses: a systematic review

Many health professionals (HPs) express discomfort at having to broach the topic of prognosis, including limited life expectancy, and may withhold information or not disclose prognosis. A systematic review was conducted of 46 studies relating to truth-telling in discussing prognosis with patients with progressive, advanced life-limiting illnesses and their caregivers. Relevant studies meeting the inclusion criteria were identified by searching computerized databases (MEDLINE, EMBASE, CINAHL, PsychINFO and Cochrane Register of Controlled Trials) up to November 2004, with handsearching of studies, as well as inclusion of studies satisfying selection criteria reported in 2005 by the authors. The reference lists of identified studies were hand-searched for further relevant studies. Inclusion criteria were studies of any design evaluating communication of prognostic information that included adult patients with an advanced, life-limiting illness; their caregivers; and qualified HPs. Results showed that although the majority of HPs believed that patients and caregivers should be told the truth about the prognosis, in practice, many either avoid discussing the topic or withhold information. Reasons include perceived lack of training, stress, no time to attend to the patient's emotional needs, fear of a negative impact on the patient, uncertainty about prognostication, requests from family members to withhold information and a feeling of inadequacy or hopelessness regarding the unavailability of further curative treatment. Studies suggest that patients can discuss the topic without it having a negative impact on them. Differences and similarities in findings from different cultures are explored.     

Neuropeptide Y Attenuates Stress‐Induced Bone Loss Through Suppression of Noradrenaline Circuits

Chronic stress and depression have adverse consequences on many organ systems, including the skeleton, but the mechanisms underlying stress‐induced bone loss remain unclear. Here we demonstrate that neuropeptide Y (NPY), centrally and peripherally, plays a critical role in protecting against stress‐induced bone loss. Mice lacking the anxiolytic factor NPY exhibit more anxious behavior and elevated corticosterone levels. Additionally, following a 6‐week restraint, or cold‐stress protocol, Npy‐null mice exhibit three‐fold greater bone loss compared to wild‐type mice, owing to suppression of osteoblast activity. This stress‐protective NPY pathway acts specifically through Y2 receptors. Centrally, Y2 receptors suppress corticotropin‐releasing factor expression and inhibit activation of noradrenergic neurons in the paraventricular nucleus. In the periphery, they act to control noradrenaline release from sympathetic neurons. Specific deletion of arcuate Y2 receptors recapitulates the Npy‐null stress response, coincident with elevated serum noradrenaline. Importantly, specific reintroduction of NPY solely in noradrenergic neurons of otherwise Npy‐null mice blocks the increase in circulating noradrenaline and the stress‐induced bone loss. Thus, NPY protects against excessive stress‐induced bone loss, through Y2 receptor‐mediated modulation of central and peripheral noradrenergic neurons. © 2014 American Society for Bone and Mineral Research.     

Response of acromegaly to long term bromocriptine therapy: a biochemical and clinical assessment.

The long term effects of bromocriptine in 12 acromegalics treated for a mean duration of 10.2 months are reported. Seven showed a significant (P less than 0.05) and sustained fall in serum immunoreactive growth hormone (GH) levels throughout 24 h, 6 of whom had a 50% or greater reduction in mean circulating GH during glucose tolerance testing. Only one patient had mean serum GH levels throughout the day suppressed to normal (less than 5 mIU/l) but 3 had suppression of mean serum GH during GTT to normal or very near normal (less than 10 mIU/l). The effective dose was 20 mg daily. Only 4 patients reported any improvement in soft tissue swelling and acral features, which was unrelated to the GH response. Possible reasons for the discrepancy between clinical and biochemical responses are discussed. In 9 of the 12 patients bromocriptine was discontinued and pituitary ablative therapy offered. Three out of 4 patients who underwent trans-sphenoidal hypophysectomy had mean GH levels during GTT reduced to less than 7 mIU/l. In the three who continued bromocriptine treatment GH suppression was maintained at less than 10 mIU/l for up to 3 years but with little change in acral features. Although bromocriptine is safe and was well tolerated it is not as effective as existing forms of pituitary ablative therapy and should be reserved for those cases where ablation is contraindicated or unsuccessful.