Caroline B. Hing

Dissemination and publication of research findings: an updated review of related biases.

OBJECTIVES To identify and appraise empirical studies on publication and related biases published since 1998; to assess methods to deal with publication and related biases; and to examine, in a random sample of published systematic reviews, measures taken to prevent, reduce and detect dissemination bias. DATA SOURCES The main literature search, in August 2008, covered the Cochrane Methodology Register Database, MEDLINE, EMBASE, AMED and CINAHL. In May 2009, PubMed, PsycINFO and OpenSIGLE were also searched. Reference lists of retrieved studies were also examined. REVIEW METHODS In Part I, studies were classified as evidence or method studies and data were extracted according to types of dissemination bias or methods for dealing with it. Evidence from empirical studies was summarised narratively. In Part II, 300 systematic reviews were randomly selected from MEDLINE and the methods used to deal with publication and related biases were assessed. RESULTS Studies with significant or positive results were more likely to be published than those with non-significant or negative results, thereby confirming findings from a previous HTA report. There was convincing evidence that outcome reporting bias exists and has an impact on the pooled summary in systematic reviews. Studies with significant results tended to be published earlier than studies with non-significant results, and empirical evidence suggests that published studies tended to report a greater treatment effect than those from the grey literature. Exclusion of non-English-language studies appeared to result in a high risk of bias in some areas of research such as complementary and alternative medicine. In a few cases, publication and related biases had a potentially detrimental impact on patients or resource use. Publication bias can be prevented before a literature review (e.g. by prospective registration of trials), or detected during a literature review (e.g. by locating unpublished studies, funnel plot and related tests, sensitivity analysis modelling), or its impact can be minimised after a literature review (e.g. by confirmatory large-scale trials, updating the systematic review). The interpretation of funnel plot and related statistical tests, often used to assess publication bias, was often too simplistic and likely misleading. More sophisticated modelling methods have not been widely used. Compared with systematic reviews published in 1996, recent reviews of health-care interventions were more likely to locate and include non-English-language studies and grey literature or unpublished studies, and to test for publication bias. CONCLUSIONS Dissemination of research findings is likely to be a biased process, although the actual impact of such bias depends on specific circumstances. The prospective registration of clinical trials and the endorsement of reporting guidelines may reduce research dissemination bias in clinical research. In systematic reviews, measures can be taken to minimise the impact of dissemination bias by systematically searching for and including relevant studies that are difficult to access. Statistical methods can be useful for sensitivity analyses. Further research is needed to develop methods for qualitatively assessing the risk of publication bias in systematic reviews, and to evaluate the effect of prospective registration of studies, open access policy and improved publication guidelines.

The results of primary Birmingham hip resurfacings at a mean of five years: AN INDEPENDENT PROSPECTIVE REVIEW OF THE FIRST 230 HIPS

We report an independent prospective review of the first 230 Birmingham hip resurfacings in 212 patients at a mean follow-up of five years (4 to 6). Two patients, one with a loose acetabular component and the other with suspected avascular necrosis of the femoral head, underwent revision. There were two deaths from unrelated causes and one patient was lost to follow-up. The survivorship with the worst-case scenario was 97.8% (95% confidence interval 95.8 to 99.5). The mean Harris hip score improved significantly (paired t-test, p < 0.05) from 62.54 (8 to 92) pre-operatively to 97.7 (61 to 100) at a mean of three years (2.1 to 4.3), then deteriorated slightly to a mean of 95.2 (47 to 100) at a mean of five years. The mean flexion improved from 91.5 degrees (25 degrees to 140 degrees) to 110.4 degrees (80 degrees to 145 degrees) at a mean of three years with no further improvement at five years (111.2 degrees; 70 degrees to 160 degrees). On radiological review at five years, one patient had a progressive lucent line around the acetabular component and six had progressive lucent lines around the femoral component. A total of 18 femoral components (8%) had migrated into varus and those with lucent lines present migrated a mean of 3.8 degrees (1.02 degrees to 6.54 degrees) more than the rest. Superolateral notching of the femoral neck and reactive sclerosis at the tip of the peg of the femoral component were associated with the presence of lucent lines (chi-squared test, p < 0.05), but not with migration of the femoral component, and are of unknown significance. Our results with the Birmingham hip resurfacing continue to be satisfactory at a mean follow-up of five years.

Narrowing of the neck in resurfacing arthroplasty of the hip: A RADIOLOGICAL STUDY

Narrowing of the femoral neck after resurfacing arthroplasty of the hip has been described previously in both cemented and uncemented hip resurfacing. The natural history of narrowing of the femoral neck is unknown. We retrospectively measured the diameter of the femoral neck in a series of 163 Birmingham hip resurfacings in 163 patients up to a maximum of six years after operation to determine the extent and progression of narrowing. There were 105 men and 58 women with a mean age of 52 years (18 to 82). At a mean follow-up of five years, the mean Harris hip score was 94.8 (47 to 100) and the mean flexion of the hip 112.5 degrees (80 degrees to 160 degrees ). There was some narrowing of the femoral neck in 77% (125) of the patients reviewed, and in 27.6% (45) the narrowing exceeded 10% of the diameter of the neck. A multiple logistic regression analysis showed a significant association (chi-squared test (derived from logistic regression) p = 0.01) of narrowing with female gender and a valgus femoral neck/shaft angle. There was no significant association between the range of movement, position or size of the component or radiological lucent lines and narrowing of the neck (chi-squared test; p = 0.10 (flexion), p = 0.08 (size of femoral component), p = 0.09 (size of acetabular component), p = 0.71 (femoral component angulation), p = 0.99 (lucent lines)). There was no significant difference between the diameter of the neck at a mean of three years (2.5 to 3.5) and that at five years (4.5 to 5.5), indicating that any change in the diameter of the neck had stabilised by three years (sign rank test, p = 0.60). We conclude that narrowing of the femoral neck which is found with the Birmingham hip resurfacing arthroplasty is in most cases associated with no adverse clinical or radiological outcome up to a maximum of six years after the initial operation.

The diagnostic accuracy of acetabular labral tears using magnetic resonance imaging and magnetic resonance arthrography: a meta-analysis

ObjectivesMagnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) have been advocated for the diagnosis of acetabular labral tears. The purpose of this study was to determine the sensitivity and specificity of MRI and MRA in diagnosing acetabular labral tears using meta-analysis.MethodsPertinent published and unpublished literature databases were reviewed. A two-by-two table was constructed to calculate the sensitivity and specificity of MRI or MRA investigations against surgical outcomes. Pooled sensitivity and specificity and Receiver Operating Characteristic curve (ROC) evaluations were performed. Methodological quality of each study was assessed using the QUADAS (Quality Assessment of Diagnostic Accuracy Studies) tool.ResultsNineteen papers assessing 881 hips were reviewed. Conventional MRI was assessed in 13 studies and MRA was assessed in 16 studies. Whilst both MRI (0.5–3T) and MRA (0.5–3T) presented with a moderate sensitivity and specificity (sensitivity 66%, 87%; specificity 79%, 64%), diagnostic accuracy of MRA appeared to be superior to MRI in detecting acetabular labral tears on ROC curve interpretation. The literature poorly described population characteristics, assessor blinding, with limited sample sizes.ConclusionsMRI and MRA may be useful adjuncts in the diagnosis of acetabular labral tears in adults. MRA appears to be superior to conventional MRI.

Extent of publication bias in different categories of research cohorts: a meta-analysis of empirical studies

BackgroundThe validity of research synthesis is threatened if published studies comprise a biased selection of all studies that have been conducted. We conducted a meta-analysis to ascertain the strength and consistency of the association between study results and formal publication.MethodsThe Cochrane Methodology Register Database, MEDLINE and other electronic bibliographic databases were searched (to May 2009) to identify empirical studies that tracked a cohort of studies and reported the odds of formal publication by study results. Reference lists of retrieved articles were also examined for relevant studies. Odds ratios were used to measure the association between formal publication and significant or positive results. Included studies were separated into subgroups according to starting time of follow-up, and results from individual cohort studies within the subgroups were quantitatively pooled.ResultsWe identified 12 cohort studies that followed up research from inception, four that included trials submitted to a regulatory authority, 28 that assessed the fate of studies presented as conference abstracts, and four cohort studies that followed manuscripts submitted to journals. The pooled odds ratio of publication of studies with positive results, compared to those without positive results (publication bias) was 2.78 (95% CI: 2.10 to 3.69) in cohorts that followed from inception, 5.00 (95% CI: 2.01 to 12.45) in trials submitted to regulatory authority, 1.70 (95% CI: 1.44 to 2.02) in abstract cohorts, and 1.06 (95% CI: 0.80 to 1.39) in cohorts of manuscripts.ConclusionDissemination of research findings is likely to be a biased process. Publication bias appears to occur early, mainly before the presentation of findings at conferences or submission of manuscripts to journals.

Is a tourniquet beneficial in total knee replacement surgery?: A meta-analysis and systematic review

Proponents of tourniquets postulate that they optimise intra-operative visibility and reduce blood loss. This study compared the outcomes of tourniquet assisted to non-tourniquet assisted total knee replacement (TKR). A systematic review was undertaken of the electronic databases Medline, CINAHL, AMED and EMBASE, in addition to a review of unpublished material and a hand search of pertinent orthopaedic journals. The evidence-base was critically appraised using a tool from the Cochrane Bone, Joint and Muscle Trauma Group. Fifteen studies were identified evaluating 16 outcome measures and parameters of 1040 TKRs in 991 patients. There was a significantly greater intra-operative blood loss in non-tourniquet compared to tourniquet assisted surgery (p=0.004). There was no significant difference between the groups for total blood loss or transfusion rate (p=0.22; p=0.48). There was a trend for greater complications in tourniquet compared to non-tourniquet patients. There was no difference between the groups for any other outcome measure assessed. In conclusion, this systematic review has found that there is no advantage to using a tourniquet in knee replacement surgery for reduction of transfusion requirements.

Diagnostic accuracy of ultrasound for rotator cuff tears in adults: a systematic review and meta-analysis.

AIM To determine the diagnostic accuracy of ultrasound to detect partial and complete thickness rotator cuff tears based on all available clinical trials. MATERIALS AND METHODS An electronic search of databases registering published and unpublished literature was conducted. All diagnostic accuracy studies that directly compared the accuracy of ultrasound (the index test) to either arthroscopic or open surgical findings (the reference test) for rotator cuff tear were included. The methodological quality of each included study was assessed using the QUADAS form. When appropriate, pooled sensitivity and specificity analysis was conducted, with an assessment of the summary receiver operating characteristic (ROC) curve for each analysis. RESULTS Sixty-two studies assessing 6007 patients and 6066 shoulders were included. Ultrasonography had good sensitivity and specificity for the assessment of partial thickness (sensitivity 0.84; specificity 0.89), and full-thickness rotator cuff tears (sensitivity 0.96; specificity 0.93). However, the literature poorly described population characteristics, assessor blinding, and was based on limited sample sizes. The literature assessing transducer frequency was particularly small in size. CONCLUSION Ultrasonography is an appropriate radiological technique for the assessment of rotator cuff tears with an acceptable sensitivity and specificity. The diagnostic test accuracy of ultrasound is superior for the detection of full-thickness compared to partial-thickness cuff tears. Further study assessing the effect of transducer frequency is warranted.

Minimally invasive versus conventional exposure for total hip arthroplasty: a systematic review and meta-analysis of clinical and radiological outcomes.

Over the past decade, minimally invasive surgery has gained popularity as a means of optimising early postoperative rehabilitation and increasing patient satisfaction and cosmesis following total hip arthroplasty (THA). However, this surgical exposure has also been associated with increased risk of iatrogenic nerve injury and implant mal-positioning due to limited visibility compared to conventionally larger surgical incisions. The purpose of this meta-analysis was to compare the outcomes of these two surgical exposures. A systematic review of the published and unpublished literature was conducted to include all randomised and non-randomised controlled trials comparing the clinical and radiological outcomes of minimally invasive and conventional THA procedures. In total, 28 studies met the eligibility criteria and included 2,849 hips, i.e. 1,428 minimally invasive compared to 1,421 conventional THAs. The meta-analysis of the current evidence base showed that minimally invasive THA is associated with a significantly increased risk of transient lateral femoral cutaneous nerve palsy (p = 0.006) with no significantly better outcome.

A meta-analysis of randomised controlled trials comparing conventional to minimally invasive approaches for repair of an Achilles tendon rupture

Achilles tendon ruptures are a common injury afflicting predominantly the young male occasional sportsman. Previous studies have shown that outcome is better with surgical repair for the young active patient. There is no consensus as to whether there is a difference in outcome between open and percutaneous minimally invasive surgery (MIS). A meta-analysis was undertaken to compare the clinical outcomes of MIS with conventional open surgical repair. Six randomised controlled trials of 277 Achilles tendon repairs were eligible for review. This included 136 minimally invasive repairs and 141 conventional open repairs. On analysis, there was no significant difference between the two surgical approaches in respect to the incidence of re-rupture, tissue adhesion, sural nerve injury, deep infection and deep vein thrombosis (p>0.05). However, MIS had a significantly reduced risk of superficial wound infection, with three times greater patient satisfaction for good to excellent results compared with conventional open surgical approaches.

The reliability and validity of radiological assessment for patellar instability. A systematic review and meta-analysis

ObjectiveTo determine the discriminative validity and reliability of the evidence base using meta-analysis.Materials and MethodsA review of published sources using the databases AMED, CINHAL, EMBASE, MEDLINE, Scopus and the Cochrane Library, and for unpublished material was conducted. All studies assessing the reliability, validity, sensitivity or specificity of magnetic resonance imaging (MRI), computed tomography (CT) or ultrasound (US) of the patellofemoral joint of patients following patellar dislocation, subluxation or instability, were included. A meta-analysis was performed to assess the difference in radiological measurements between healthy controls and subjects with patellar instability in order to assess discrimination validity. A narrative assessment was used to evaluate the inter- and intra-observer reliability as well as the sensitivity and specificity of specific radiological measurements.ResultsA total of 27 studies were reviewed. The findings indicated that there was acceptable inter-observer and intra-observer reliability and validity for different methods of assessing patellar height and the sulcus angle with X-ray, MRI and CT methods, and the tibial tubercle-trochlear groove (TT-TG) assessed using CT. There was poor reliability or validity for the assessment of severity of trochlear dysplasia and the sulcus angle using US.ConclusionThere is insufficient evidence to determine the reliability, validity, sensitivity or specificity of tests such as the congruence angle, lateral patellar displacement, lateral patellar tilt, trochlear depth, boss height, the crossing sign or Wiberg patellar classification. A critical appraisal of the literature identified a number of recurrent methodological limitations. Further study is recommended to evaluate the reliability and validity of these radiological outcomes using well-designed radiological trials.