Sample size calculation in physical medicine and rehabilitation: a systematic review of reporting, characteristics, and results in randomized controlled trials

Abdul Latif L, Daud Amadera JE, Pimentel D, Pimentel T, Fregni F. Sample size calculation in physical medicine and rehabilitation: a systematic review of reporting, characteristics, and results in randomized controlled trials.

Objective

To assess systematically the reporting of sample size calculation in randomized controlled trials (RCTs) in 5 leading journals in the field of physical medicine and rehabilitation (PM&R).

Data Sources

The data source was full reports of RCTs in 5 leading PM&R journals (Journal of Rehabilitation Medicine, Archives of Physical Medicine and Rehabilitation, American Journal of Physical Medicine and Rehabilitation, Clinical Rehabilitation, and Disability and Rehabilitation) between January and December of 1998 and 2008. Articles were identified in Medline.

Study Selection

A total of 111 articles met our inclusion criteria, which include RCTs of human studies in the 5 selected journals.

Data Extraction

Sample size calculation reporting and trial characteristics were collected for each trial by independent investigators.

Data Synthesis

In 2008, 57.3% of articles reported sample size calculation as compared with only 3.4% in 1998. The parameters that were commonly used were a power of 80% and alpha of 5%. Articles often failed to report effect size or effect estimates for sample size calculation. Studies reporting sample size calculation were more likely to describe the main outcome and to have a sample size greater than 50 subjects. The study outcome (positive vs negative) was not associated with the likelihood of sample size reporting. Trial characteristics of the 2 periods (1998 vs 2008) were similar except that in 1998 there were more negative studies compared with 2008.

Conclusions

Although sample size calculation reporting has improved dramatically in 10 years and is comparable with other fields in medicine, it is still not adequate given current publication guidelines.     

A phylogenetic study of hepatitis B virus in chronically infected Brazilian patients of Western and Asian descent

Background  Hepatitis B virus (HBV) causes one of the most important chronic viral infections worldwide. HBV is classified into eight genotypes whose epidemiology varies geographically. In Brazil, genotypes A, D, and F are more frequent, while in East Asia, genotypes B and C predominate. Several studies showed that immigrants retain the HBV infection pattern of their ancestral country. Purpose  To identify HBV genotypes infecting chronic carriers in Brazilian families of Western and Asian descent by Hepatitis B surface antigen gene sequencing and analyze the route of viral transmission by phylogenetic analysis of viral sequences. Methods  Eighty-seven people chronically infected with HBV were separated into two groups: Western descent (27) and Asian descent (60). Surface and pre-core/core genes were amplified from serum HBV-DNA and sequences were subjected to phylogenetic analysis. Results  HBV genotype A was found in 74% of Western subjects, while genotype C was found in 94% of Asian patients. Thirty-eight percent of Western families were infected with HBV with similar pre-core/core sequences, while only 25% of Asian families showed similarity in these sequences. Conclusions  Phylogenetical analysis of pre-core/core HBV gene suggested intra-familial transmission of HBV in 38% of Western families and 25% of Asian families. Analysis of HBsAg gene sequences helped to define the HBV genotype but did not allow inferring route of transmission as its sequences showed a smaller phylogenetic signal than pre-core/core sequences. Chronic HBV carriers of Asian descent born in or living in Brazil were infected with the same HBV genotype predominant in their ancestral country.     

Association of frailty with short-term outcomes,organ support and resource use in critically ill patients

Purpose

Frail patients are known to experience poor outcomes. Nevertheless, we know less about how frailty manifests itself in patients’ physiology during critical illness and how it affects resource use in intensive care units (ICU). We aimed to assess the association of frailty with short-term outcomes and organ support used by critically ill patients.

Methods

Retrospective analysis of prospective collected data from 93 ICUs in Brazil from 2014 to 2015. We assessed frailty using the modified frailty index (MFI). The primary outcome was in-hospital mortality. Secondary outcomes were discharge home without need for nursing care, ICU and hospital length of stay (LOS), and utilization of ICU organ support and transfusion. We used mixed logistic regression and competing risk models accounting for relevant confounders in outcome analyses.

Results

The analysis consisted of 129,680 eligible patients. There were 40,779 (31.4%) non-frail (MFI?=?0), 64,407 (49.7%) pre-frail (MFI?=?1–2) and 24,494 (18.9%) frail (MFI?≥?3) patients. After adjusted analysis, frailty was associated with higher in-hospital mortality (OR 2.42, 95% CI 1.89–3.08), particularly in patients admitted with lower SOFA scores. Frail patients were less likely to be discharged home (OR 0.36, 95% CI 0.54–0.79) and had higher hospital and ICU LOS than non-frail patients. Use of all forms of organ support (mechanical ventilation, non-invasive ventilation, vasopressors, dialysis and transfusions) were more common in frail patients and increased as MFI increased.

Conclusions

Frailty, as assessed by MFI, was associated with several patient-centered endpoints including not only survival, but also ICU LOS and organ support.

     

Myeloperoxidase gene polymorphism predicts fibrosis severity in women with hepatitis C

Oxidative stress plays an important role on liver fibrosis progression in the course of hepatitis C virus (HCV) infection. Myeloperoxidase (MPO) is an enzyme released by neutrophils and macrophages, responsible for generating hypochlorous acid and reactive oxygen species (ROS) that may lead to liver injury in HCV infection. On the other hand, antioxidant enzymes such as manganese superoxide dismutase (SOD) controls ROS-mediated damage. The aim of the present study was to investigate the influence of MPO G-463A and SOD2 Ala16Val polymorphisms in the severity of liver fibrosis in individuals with chronic HCV infection. The present study included 270 patients with chronic HCV recruited from the Gastrohepatology Service of the Oswaldo Cruz University Hospital/Liver Institute of Pernambuco (Recife, Northeastern Brazil). All patients underwent liver biopsy, which was classified according METAVIR score. The SNPs were determined by real-time PCR. After multivariate analysis adjustment, the GG genotype of MPO and the presence of metabolic syndrome were independently associated with fibrosis severity in women (P = 0.025 OR 2.25 CI 1.10–4.59 and P = 0.032 OR 2.32 CI 1.07–5.01, respectively). The presence of the GG genotype seems to be a risk factor for fibrosis severity in women with HCV.     

Inhibin alpha-subunit (INHA) gene and locus changes in paediatric adrenocortical tumours from TP53 R337H mutation heterozygote carriers

The R337H TP53 mutation is a low-penetrance molecular defect that predisposes to adrenocortical tumour (ACT) formation in Brazilian and possibly other populations. Additional genetic defects may be responsible for the variable expression of ACTs in these cases. The inhibin α-subunit gene (INHA) on 2q33-qter has been implicated in mouse adrenocortical tumourigenesis. We studied 46 pediatric patients with ACTs from Brazil for INHA genetic alterations; 39 of these patients were heterozygous carriers of the R337H TP53 mutation. We first mapped the INHA gene by radiation hybrid analysis and determined 10 linked microsatellite markers in an area flanked by D2S1371 and D2S206 on 2q33-qter. These markers were then used for loss of heterozygozity (LOH) studies in nine paired germline and tumour DNA samples. Mapping placed the INHA gene in close proximity to D2S2848 (SHGC11864) with a log of odds (LOD) score of 5.84. LOH for at least one marker in the region was identified in 8/9 tumours (89%). Six patients were heterozygous for three INHA mutations: one in exon 1, 127C>G, and two in exon 2, 3998G>A and 4088G>A, all leading to amino acid substitutions (P43A, G227R, and A257T, respectively). A257T is located in a conserved INHA region, highly homologous to transforming growth factor-ß; both G227R and A257T change polarity, and, in addition, G227R changes the pH. We conclude that these sequence alterations and the detected 2q allelic changes suggest that INHA may be one of the contributing factors needed for ACT formation in pediatric patient carriers of the R337H TP53 mutation.     

Evaluation of Gamma Interferon Immune Response Elicited by the Newly Constructed PstS-1(285-374):CFP10 Fusion Protein To Detect Mycobacterium tuberculosis Infection

The PstS1 antigen is highly immunogenic, principally when combined with CFP10 during both latent and active TB infection. In the present study, a selected pstS1 gene fragment was cloned, fused with CFP10, and expressed in Escherichia coli. The product [PstS-1(285-374):CFP10] was compared to the recombinant fused RD1 (region of deletion 1) protein (ESAT-6:CFP10) in detecting Mycobacterium tuberculosis infection in 108 recent contacts of pulmonary tuberculosis (TB) cases, considering a positive tuberculin skin test (TST) to be the baseline. The release of gamma interferon (IFN-γ) in 22-h whole-blood and 5-day lymphocyte stimulation assays primed with each antigen was determined. All contacts were clinically followed for up to 1 year, and 87% of the tuberculin skin test-positive (TST^positive) patients accepted preventative treatment. Concerning the IFN-γ response to PstS-1(285-374):CFP10 in the 22-h and 5-day assays, a slight increase in contact-TST^positive detection was observed (23/54 and 26/54) compared to the level seen with the RD1 protein (18/54 and 24/54) whereas in the TST^negative group, similarly lower numbers (≤5/48) of responders were achieved for both antigens, except for RD1 in the 5-day assay (8/48). By combining the IFN-γ responders to both antigens in the 5-day assays, slightly higher increases in positivity were found in the TST^positive (32/54) and TST^negative (10/48) groups. Two of 12 untreated TST^positive contacts progressed to active TB and were concordantly positive in all assays, except for one contact who lacked positivity in the RD1 5-day assay. We demonstrated for the first time that PstS-1(285-374):CFP10 slightly increased contact positivity and detection of active disease progression, suggesting its potential application as a TB infection marker.     

Amiodarone Surveillance in Primary Care

Amiodarone is a drug commonly used in primary care practice to treat serious cardiac arrhythmias. While efficacious, this drug places patients at risk for serious adverse events, and ongoing surveillance is essential. The purpose of this article is 2-fold: summarize pharmacokinetics of amiodarone and potential adverse effects and present current, expert, consensus panel recommendations for surveillance. The methods used are review of relevant literature and creation of quick review tables that may be applied to clinical practice. The intent of this article is to promote improved patient safety and care quality for patients receiving long-term amiodarone therapy.