Persistency of Pseudomonas aeruginosa in sputum cultures and clinical outcomes in adult patients with cystic fibrosis

Our objective was to describe the natural history of infection with transmissible and unique strains of P. aeruginosa (PA) in adult CF patients and to determine if clearance of PA from sputum was associated with an improvement in clinical status. This was a 3-year prospective cohort study of adult patients with CF. Sputum was collected at baseline and annually. Rate of decline of FEV1, BMI, exacerbation rate, and time to death or transplant were compared between patients who cleared PA versus those in whom PA was persistent. A total of 373 patients were included in the study, 75% were infected with PA at baseline; 24% were infected with transmissible strains and 51% with unique strains. Patients infected with unique strains were more likely to clear PA from their sputum over 3 years compared to those infected with transmissible strains (19% vs 10%, P=0.05). Declines in FEV1 and rates of pulmonary exacerbations, deaths, or lung transplants were not different between patients who cleared PA compared to those who remained persistently infected. No clinical benefit was identified in patients who cleared PA from sputum compared to those who remained persistently infected.

Renin angiotensin system blockade in kidney transplantation: a systematic review of the evidence

ACE-inhibitors and angiotensin receptor blockers (ARB) slow the progression of renal disease in non-transplant patients. A systematic review of randomized trials (n = 21 trials with 1549 patients) was conducted to determine the effect of ACE-inhibitor or ARB use following kidney transplantation. With a median follow-up of 27 months, ACE-inhibitor or ARB use was associated with a significant decrease in glomerular filtration rate (-5.8 mL/min; 95% CI -10.6 to -0.99). ACE-inhibitor or ARB use resulted in a lower hematocrit (-3.5%; 95% CI -6.1 to -0.95), reduction in proteinuria (-0.47 gm/d; 95% CI -0.86 to -0.08) but no change in the serum potassium (0.18 mmol/L; 95% CI -0.03 to 0.40). ACE-inhibitor or ARB use results in clinically important reductions in proteinuria, hematocrit and glomerular filtration rate in renal transplant recipients, but there are insufficient data to determine the effect on patient or graft survival. Randomized trials of sufficient power and duration that examine these hard outcomes should be conducted. Until such trials are completed, this study provides quantitative estimates of the risks and benefits of ACE-inhibitor or ARB use that can be used by clinicians considering prescribing these medications to kidney transplant recipients or to researchers designing future trials.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery and previous reviews have found them to be effective in reducing blood loss and the need for transfusion. Recently, questions have been raised regarding the comparative performance of the drugs and the safety of the most popular agent, aprotinin.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, and the internet. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

This review summarises data from 211 RCTs that recruited 20,781 participants. Data from placebo/inactive controlled trials, and from head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of operative blood loss, but the differences were small. Aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.61 to 0.71). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.54 to 0.69) and it was 0.75 (95% CI 0.58 to 0.96) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared superior in reducing the need for RBC transfusion: RR 0.83 (95% CI 0.69 to 0.99). Aprotinin reduced the need for re-operation due to bleeding: RR 0.48 (95% CI 0.35 to 0.68). This translates into an absolute risk reduction of just under 3% and a number needed-to-treat (NNT) of 37 (95% CI 27 to 56). Similar trends were seen with TXA and EACA, but the data were sparse and the differences failed to reach statistical significance. The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias. Evidence of publication bias was not observed in trials reporting re-operation rates. Adjustment for these effects reduced the magnitude of estimated benefits but did not negate treatment effects. However, the apparent advantage of aprotinin over the lysine analogues was small and may be explained by publication bias and non-equivalent drug doses. Aprotinin did not increase the risk of myocardial infarction (RR 0.92, 95% CI 0.72 to 1.18), stroke (RR 0.76, 95% CI 0.35 to 1.64) renal dysfunction (RR 1.16, 95% CI 0.79 to 1.70) or overall mortality (RR 0.90, 95% CI 0.67 to 1.20). The analyses of myocardial infarction and death included data from the majority of subjects recruited into the clinical trials of aprotinin. However, under-reporting of renal events could explain the lack of effect seen with aprotinin. Similar trends were seen with the lysine analogues but data were sparse. These results conflict with the results of recently published non-randomised studies.

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the need for allogeneic red cell transfusion. Based on the results of randomised trials their efficacy does not appear to be offset by serious adverse effects. In most circumstances the lysine analogues are probably as effective as aprotinin and are cheaper; the evidence is stronger for tranexamic acid than for aminocaproic acid. In high risk cardiac surgery, where there is a substantial probability of serious blood loss, aprotinin may be preferred over tranexamic acid. Aprotinin does not appear to be associated with an increased risk of vascular occlusion and death, but the data do not exclude an increased risk of renal failure. There is no need for further placebo-controlled trials of aprotinin or lysine analogues in cardiac surgery. The principal need is for large comparative trials to assess the relative efficacy, safety and cost-effectiveness of anti-fibrinolytic drugs in different surgical procedures.

Renin angiotensin system blockade in kidney transplantation: a systematic review of the evidence

ACE-inhibitors and angiotensin receptor blockers (ARB) slow the progression of renal disease in non-transplant patients. A systematic review of randomized trials (n = 21 trials with 1549 patients) was conducted to determine the effect of ACE-inhibitor or ARB use following kidney transplantation. With a median follow-up of 27 months, ACE-inhibitor or ARB use was associated with a significant decrease in glomerular filtration rate (-5.8 mL/min; 95% CI -10.6 to -0.99). ACE-inhibitor or ARB use resulted in a lower hematocrit (-3.5%; 95% CI -6.1 to -0.95), reduction in proteinuria (-0.47 gm/d; 95% CI -0.86 to -0.08) but no change in the serum potassium (0.18 mmol/L; 95% CI -0.03 to 0.40). ACE-inhibitor or ARB use results in clinically important reductions in proteinuria, hematocrit and glomerular filtration rate in renal transplant recipients, but there are insufficient data to determine the effect on patient or graft survival. Randomized trials of sufficient power and duration that examine these hard outcomes should be conducted. Until such trials are completed, this study provides quantitative estimates of the risks and benefits of ACE-inhibitor or ARB use that can be used by clinicians considering prescribing these medications to kidney transplant recipients or to researchers designing future trials.

Counting, analysing and reporting exacerbations of COPD in randomised controlled trials

BACKGROUND

Clinical trials measure exacerbations of chronic obstructive pulmonary disease (COPD) inconsistently. A study was undertaken to determine if different methods for ascertaining and analysing COPD exacerbations lead to biased estimates of treatment effects.

METHODS

Information on the methods used to count, analyse and report COPD exacerbation rates was abstracted from clinical trials of long-acting bronchodilators or long-acting bronchodilator/inhaled steroid combination products published between 2000 and 2006. Data from the Canadian Optimal Therapy of COPD Trial was used to illustrate how different analytical approaches can affect the estimate of exacerbation rates and their confidence intervals.

RESULTS

22 trials (17,156 patients) met the inclusion criteria and were reviewed. None of the trials adjudicated exacerbations or determined independence of events. 14/22 studies (64%) introduced selection bias by not analysing outcome data for subjects who prematurely stopped study medications. Only 31% of trials used time-weighted analyses to calculate the mean number of exacerbations/patient-year and only 15% accounted for between-subject variation. In the Canadian Optimal Therapy of COPD Trial the rate ratio for exacerbations/patient-year was 0.85 when all data were included in a time-weighted analysis, but was overestimated as 0.79 when data for those who prematurely stopped study medications were excluded and was further overestimated as 0.46 when a time-weighted analysis was not conducted; p values ranged from 0.03 to 0.24 depending on how exacerbations were determined and analysed.

CONCLUSIONS

Clinical trials have used widely different methods to define and analyse COPD exacerbations and this can lead to biased estimates of treatment effects. Future trials should strive to include blinded adjudication and assessment of the independence of exacerbation events, and trials should report time-weighted intention-to-treat analyses with adjustments for between-subject variation in COPD exacerbations.

Use of intravenous immunoglobulin for treatment of recurrent miscarriage: a systematic review

BACKGROUND

Intravenous immunoglobulin (IVIG) is a fractionated blood product whose off-label use for treating a variety of conditions, including spontaneous recurrent miscarriage, has continued to grow in recent years. Its high costs and short supply necessitate improved guidance on its appropriate applications.

OBJECTIVE

We conducted a systematic review of randomised controlled trials evaluating IVIG for treatment of spontaneous recurrent miscarriage.

SEARCH STRATEGY

A systematic search strategy was applied to Medline (1966 to June 2005) and the Cochrane Register of Controlled Trials (June 2005).

SELECTION CRITERIA

We included all randomised controlled trials comparing all dosages of IVIG to placebo or an active control.

DATA COLLECTION AND ANALYSIS

Two investigators independently extracted data using a standardised data collection form. Measures of effect were derived for each trial independently, and studies were pooled based on clinical and methodologic appropriateness.

MAIN RESULTS

We identified eight trials involving 442 women that evaluated IVIG therapy used to treat recurrent miscarriage. Overall, IVIG did not significantly increase the odds ratio (OR) of live birth when compared with placebo for treatment of recurrent miscarriage (OR 1.28, 95% CI 0.78-2.10). There was, however, a significant increase in live births following IVIG use in women with secondary recurrent miscarriage (OR 2.71, 95% CI 1.09-6.73), while those with primary miscarriage did not experience the same benefit (OR 0.66, 95% CI 0.35-1.26).

AUTHOR'S CONCLUSIONS

IVIG increased the rates of live birth in secondary recurrent miscarriage, but there was insufficient evidence for its use in primary recurrent miscarriage.

Predictors of pulmonary exacerbations in patients with cystic fibrosis infected with multi-resistant bacteria

BACKGROUND

This study examined characteristics of adult and adolescent patients with cystic fibrosis (CF) to determine factors associated with an increased risk of pulmonary exacerbations.

METHODS

249 patients with CF infected with multidrug resistant bacteria were recruited and prospectively followed for up to 4.5 years until they experienced a pulmonary exacerbation severe enough to require intravenous antibiotics. Multivariable regression analyses were used to compare the characteristics of patients who experienced an exacerbation with those who did not.

RESULTS

124 of the 249 patients (50%) developed a pulmonary exacerbation during the first year and 154 (62%) experienced an exacerbation during the 4.5 year study period. Factors predictive of exacerbations in a multivariable survival model were younger age (OR 0.98, 95% CI 0.96 to 0.99), female sex (OR 1.45, 95% CI 1.07 to 1.95), lower forced expiratory volume in 1 second (FEV(1)) (OR 0.98, 95% CI 0.97 to 0.99), and a previous history of multiple pulmonary exacerbations (OR 3.16, 95% CI 1.93 to 5.17). Chronic use of inhaled corticosteroids was associated with an increased risk of exacerbation (OR 1.92, 95% CI 1.00 to 3.71) during the first study year.

CONCLUSIONS

Patients who experience pulmonary exacerbations are more likely to be younger, female, using inhaled steroids, have a lower FEV(1), and a history of multiple previous exacerbations. It is hoped that knowledge of these risk factors will allow better identification and closer monitoring of patients who are at high risk of exacerbations.

Re-evaluation of randomized control trials of lithium monotherapy: a cohort effect

OBJECTIVE

The reported reduction of lithium's efficacy in the prophylaxis of bipolar illness has been attributed to various factors, including diagnostic changes and heterogeneous study designs. We attempted to quantify the impact of pre-randomization enrichment designs and diagnostic drift on randomized controlled trials (RCTs) of lithium maintenance therapy.

METHODS

Using the Cochrane RCT search filter, MEDLINE, EMBASE, and PSYCHINFO were searched (1966 to June 2004) for all available randomized studies using the text word 'lithium'. Studies of 1 year minimum duration in bipolar disorder involving lithium and placebo arms were identified. Superiority trials without a placebo arm, discontinuation and mirror image studies were excluded. Standardized scales were used to assess randomization and allocation concealment.

RESULTS

Nine RCTs enrolling 1432 bipolar I and II patients, randomizing 341 to lithium and 386 to placebo were identified, with 705 reported pre-randomization dropouts. The pooled odds of remaining recurrence free in two non-enriched RCTS using Research Diagnostic Criteria (RDC) or Feighner criteria were 3.2:1 (95% CI 0.65--15.46) trending in favor of lithium over placebo, and 22.0:1 (95% CI 7.0--68.7) for three trials using lithium enrichment and excluding atypical bipolar disorder. The odds of remaining recurrence free using DSM-IV criteria and lamotrigine enrichment were 1.9:1 (95% CI 1.2-2.8).

CONCLUSION

Lithium maintenance RCTs differ in patient selection, design, and outcome. A cohort effect can be associated with the use of pre-randomization enrichment phases and, to a lesser extent, with diagnostic drift, compromising straightforward comparisons across three decades of lithium monotherapy in bipolar illness.

The cost of allogeneic red blood cells - a systematic review

Several reports suggest that the cost of RBCs may have risen over time, but there exists very little published evidence of that. The objective was to determine whether published studies documenting cost data on RBCs suggest an increase over time and to assess the quality of cost studies. We used the terms 'cost', 'allogeneic/allogenic' and 'blood' to identify cost studies between 1966 and 2002 from Medline, ISIesource and Ingenta electronic databases. Furthermore, we manually searched a number of transfusion and health economics journals for completeness. We included studies that used an established methodology and conducted an economic evaluation using primary/secondary cost data to calculate the cost of RBCs and RBC transfusion. Studies without allogeneic RBCs as comparator were excluded. Two individuals independently reviewed the studies and included studies upon reaching a consensus. Fourteen studies qualified the selection criteria and were included in the review. Ten studies were identified from Medline, two from Ingenta, one from ISIesource and one was a conference paper. Of the 14 studies reviewed, 10 had focused on RBC transfusion and four had focused on both RBCs and RBC transfusion. Ten studies were from the US, and two each from Canada and the UK, respectively. Two studies had explicit objective of cost calculation, and others had calculated costs towards fulfilling other objectives. Most of the reviewed studies were dated and of poor quality. Despite these limitations, it appears that the cost of RBCs has increased over time in the UK, Canada and the US. More studies are needed to fully assess the trend of costs over time. Future cost studies should try to follow the economic evaluation guidelines for greater research implications.

Pre-operative autologous donation for minimising perioperative allogeneic blood transfusion

BACKGROUND

Public concerns regarding the safety of transfused blood have prompted re-consideration of the indications for the transfusion of allogeneic red cells (blood from an unrelated donor), and a range of techniques designed to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of pre-operative autologous blood donation (PAD) in reducing the need for peri-operative allogeneic red blood cell (RBC) transfusion.

SEARCH STRATEGY

Articles were identified by: computer searches of OVID MEDLINE, EMBASE, and Current Contents (to March 2001) and web sites of international health technology assessment agencies (to January 2001). References in the identified trials were checked and authors contacted to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to PAD, or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al (1995) and Jadad et al (1996). The principle outcomes were: the number of patients exposed to allogeneic red blood cells, and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

Overall PAD reduced the risk of receiving an allogeneic blood transfusion by a relative 63% (RR=0.37: 95%CI:0.26,0.54). The absolute reduction in risk of allogeneic transfusion was 43.8% (RD=-0.438: 95%CI: -0.607,-0.268). In contrast the results show that the risk of receiving any blood transfusion (allogeneic and/or autologous) is actually increased by pre-operative autologous blood donation (RR=1.29: 95%CI: 1.12,1.48). Trials were unblinded and allocation concealment was not described in 87.5% of the trials.

REVIEWER'S CONCLUSIONS

Although the trials of PAD showed a reduction in the need for allogeneic blood the methodological quality of the trials was poor and the overall transfusion rates (allogeneic and/or autologous) in these trials were high, and were increased by recruitment into the PAD arms of the trials. This raises questions about the true benefit of PAD. In the absence of large, high quality trials using clinical endpoints, it is not possible to say whether the benefits of PAD outweigh the harms.