Which resources should be used to identify RCT/CCTs for systematic reviews: a systematic review

The association of depression with adherence to antihypertensive medications: a systematic review

OBJECTIVE

To examine the strength and consistency of the evidence on the relationship between depression and adherence to antihypertensive medications.

METHODS

The MEDLINE, CINAHL, PsycINFO, Embase, SCOPUS, and ISI databases were searched from inception until 11 December 2009 for published studies of original research that assessed adherence to antihypertensive medications and used a standardized interview, validated questionnaire, or International Classification of Diseases Ninth Revision code to assess depression or symptoms of depression in patients with hypertension. Manual searching was conducted on 22 selected journals. Citations of included articles were tracked using Web of Science and Google Scholar. Two investigators independently extracted data from the selected articles and discrepancies were resolved by consensus.

RESULTS

Eight studies were identified that included a total of 42,790 patients. Ninety-five percent of these patients were from one study. Only four of the studies had the assessment of this relationship as a primary objective. Adherence rates varied from 29 to 91%. There were widely varying results within and across studies. All eight studies reported at least one significant bivariate or multivariate negative relationship between depression and adherence to antihypertensive medications. Insignificant findings in bivariate or multivariate analyses were reported in six of eight studies.

CONCLUSION

All studies reported statistically significant relationships between depression and poor adherence to antihypertensive medications, but definitive conclusions cannot be drawn because of substantial heterogeneity between studies with respect to the assessment of depression and adherence, as well as inconsistencies in results both within and between studies. Additional studies would help clarify this relationship.

Methodological quality of a systematic review on physical therapy for temporomandibular disorders: influence of hand search and quality scales

The validity of a systematic review depends on completeness of identifying randomised clinical trials (RCTs) and the quality of the included RCTs. The aim of this study was to analyse the effects of hand search on the number of identified RCTs and of four quality lists on the outcome of quality assessment of RCTs evaluating the effect of physical therapy on temporomandibular disorders. In addition, we investigated the association between publication year and the methodological quality of these RCTs. Cochrane, Medline and Embase databases were searched electronically. The references of the included studies were checked for additional trials. Studies not electronically identified were labelled as “obtained by means of hand search”. The included RCTs (69) concerning physical therapy for temporomandibular disorders were assessed using four different quality lists: the Delphi list, the Jadad list, the Megens & Harris list and the Risk of Bias list. The association between the quality scores and the year of publication were calculated. After electronic database search, hand search resulted in an additional 17 RCTs (25%). The mean quality score of the RCTs, expressed as a percentage of the maximum score, was low to moderate and varied from 35.1% for the Delphi list to 54.3% for the Risk of Bias list. The agreement among the four quality assessment lists, calculated by the Interclass Correlation Coefficient, was 0.603 (95% CI, 0.389; 0.749). The Delphi list scored significantly lower than the other lists. The Risk of Bias list scored significantly higher than the Jadad list. A moderate association was found between year of publication and scores on the Delphi list (r = 0.50), the Jadad list (r = 0.33) and the Megens & Harris list (r = 0.43).

Not published, not indexed: issues in generating and finding hospice and palliative care literature

INTRODUCTION

Accessing new knowledge as the evidence base for hospice and palliative care grows has specific challenges for the discipline. This study aimed to describe conversion rates of palliative and hospice care conference abstracts to journal articles and to highlight that some palliative care literature may not be retrievable because it is not indexed on bibliographic databases.

METHODS

Substudy A tracked the journal publication of conference abstracts selected for inclusion in a gray literature database on www.caresearch.com.au . Abstracts were included in the gray literature database following handsearching of proceedings of over 100 Australian conferences likely to have some hospice or palliative care content that were held between 1980 and 1999. Substudy B looked at indexing from first publication until 2001 of three international hospice and palliative care journals in four widely available bibliographic databases through systematic tracing of all original papers in the journals.

RESULTS

Substudy A showed that for the 1338 abstracts identified only 15.9% were published (compared to an average in health of 45%). Published abstracts were found in 78 different journals. Multiauthor abstracts and oral presentations had higher rates of conversion. Substudy B demonstrated lag time between first publication and bibliographic indexing. Even after listing, idiosyncratic noninclusions were identified.

DISCUSSION

There are limitations to retrieval of all possible literature through electronic searching of bibliographic databases. Encouraging publication in indexed journals of studies presented at conferences, promoting selection of palliative care journals for database indexing, and searching more than one bibliographic database will improve the accessibility of existing and new knowledge in hospice and palliative care.

Global Assessment of Functioning (GAF): properties and frontier of current knowledge

BACKGROUND

Global Assessment of Functioning (GAF) is well known internationally and widely used for scoring the severity of illness in psychiatry. Problems with GAF show a need for its further development (for example validity and reliability problems). The aim of the present study was to identify gaps in current knowledge about properties of GAF that are of interest for further development. Properties of GAF are defined as characteristic traits or attributes that serve to define GAF (or may have a role to define a future updated GAF).

METHODS

A thorough literature search was conducted.

RESULTS

A number of gaps in knowledge about the properties of GAF were identified: for example, the current GAF has a continuous scale, but is a continuous or categorical scale better? Scoring is not performed by setting a mark directly on a visual scale, but could this improve scoring? Would new anchor points, including key words and examples, improve GAF (anchor points for symptoms, functioning, positive mental health, prognosis, improvement of generic properties, exclusion criteria for scoring in 10-point intervals, and anchor points at the endpoints of the scale)? Is a change in the number of anchor points and their distribution over the total scale important? Could better instructions for scoring within 10-point intervals improve scoring? Internationally, both single and dual scales for GAF are used, but what is the advantage of having separate symptom and functioning scales? Symptom (GAF-S) and functioning (GAF-F) scales should score different dimensions and still be correlated, but what is the best combination of definitions for GAF-S and GAF-F? For GAF with more than two scales there is limited empirical testing, but what is gained or lost by using more than two scales?

CONCLUSIONS

In the history of GAF, its basic properties have undergone limited changes. Problems with GAF may, in part, be due to lack of a research programme testing the effects of different changes in basic properties. Given the widespread use, research-based development of GAF has not been especially strong. Further research could improve GAF.

Effects of antihypertensive-drug class on interindividual variation in blood pressure and risk of stroke: a systematic review and meta-analysis

INTRODUCTION

Unexplained differences between classes of antihypertensive drugs in their effectiveness in preventing stroke might be due to class effects on intraindividual variability in blood pressure. We did a systematic review to assess any such effects in randomised controlled trials.

METHODS

Baseline and follow-up data for mean (SD) of systolic blood pressure (SBP) were extracted from trial reports. Effect of treatment on interindividual variance (SD2) in blood pressure (a surrogate for within-individual variability), expressed as the ratio of the variances (VR), was related to effects on clinical outcomes. Pooled estimates were derived by use of random-effects meta-analysis.

FINDINGS

Mean (SD) SBP at follow-up was reported in 389 (28%) of 1372 eligible trials. There was substantial heterogeneity between trials in VR (p<1 x 10(-40)), 68% of which was attributable to allocated drug class. Compared with other drugs, interindividual variation in SBP was reduced by calcium-channel blockers (VR 0.81, 95% CI 0.76-0.86, p<0.0001) and non-loop diuretic drugs (0.87, 0.79-0.96, p=0.007), and increased by angiotensin-converting enzyme (ACE) inhibitors (1.08, 1.02-1.15, p=0.008), angiotensin-receptor blockers (1.16, 1.07-1.25, p=0.0002), and beta blockers (1.17, 1.07-1.28, p=0.0007). Compared with placebo only, interindividual variation in SBP was reduced the most by calcium-channel blockers (0.76, 0.67-0.85, p<0.0001). Effects were consistent in parallel group and crossover design trials, and in analyses of dose-response. Across all trials, effects of treatment on VR of SBP (r2=0.372, p=0.0006) and on mean SBP (r2=0.328, p=0.0015) accounted for effects on stroke risk (eg, odds ratio 0.79, 0.71-0.87, p<0.0001, for VR< or =0.80), and both remained significant in a combined model.

INTERPRETATION

Drug-class effects on interindividual variation in blood pressure can account for differences in effects of antihypertensive drugs on risk of stroke independently of effects on mean SBP.

FUNDING

None.

Patterns of access to community palliative care services: a literature review

Policies state that access to palliative care should be provided according to principles of equity. Such principles would include the absence of disparities in access to health care that are systematically associated with social advantage. A review of the literature a decade ago identified that patients with different characteristics used community palliative care services in variable ways that appeared inequitable. The objective of this literature review was to review recent literature to identify whether such variability remains. Searching included the use of electronic databases, scrutinizing bibliographies, and hand searching journals. Articles were included if they were published after 1997 (the date of the previous review) up to the beginning of 2008, and if they reported any data that investigated the characteristics of adult patients in relation to their relative utilization of community palliative care services, with reference to a comparator population. Forty-eight studies met the inclusion criteria. Patients still access community palliative care services in variable ways. Those who are older, male, from ethnic minority populations, not married, without a home carer, are socioeconomically disadvantaged, and who do not have cancer are all less likely to access community palliative care services. These studies do not identify the reasons for such variable access, or whether such variability is warranted with reference to clinical need or other factors. Studies tend to focus on access to specialist palliative care services without looking at the complexities of service use. Studies need to move beyond description of utilization patterns, and examine whether such patterns are inequitable, and what is happening in the referral or other processes that may result in such patterns.

Searching for unpublished trials in Cochrane reviews may not be worth the effort

OBJECTIVE

To assess the value of searching for unpublished data by exploring the extent to which Cochrane reviews include unpublished data and by evaluating the quality of unpublished trials.

STUDY DESIGN AND SETTING

We screened all 2,462 completed Cochrane reviews published since 2000 in the Cochrane Database of Systematic Reviews Issue 3, 2006. In a random sample (n=61) of 292 reviews, including unpublished trials, we studied all 116 references.

RESULTS

Unpublished trials make up 8.8% of all included trials in our sample. Thirty-eight percent of the "unpublished" trials have in fact been published. Allocation concealment was "unclear" or not adequate in 54.3% and 61.3% reported blinding. In 47.2% reported withdrawal rates were >20%. Trials that were eventually published had larger mean population sizes (P-value, 0.02). Of the reported sponsors, 87.3% were drug companies. Methodological quality and publication bias are mentioned in half of the reviews and explored in a third. Quality ratings did not have consequences for pooling, because 82.8% was included in the forest plots.

CONCLUSIONS

A minority of Cochrane reviews include "unpublished trials" and many of these are eventually published. Truly unpublished studies have poor or unclear methodological quality. Therefore, it may be better to invest in regular updating of reviews, rather than in extensive searching for unpublished data.

African HIV/AIDS trials are more likely to report adequate allocation concealment and random generation than North American trials

Background

Adherence to good methodological quality is necessary to minimise bias in randomised conrolled trials (RCTs). Specific trial characteristics are associated with better trial quality, but no studies to date are specific to HIV/AIDS or African trials. We postulated that location may negatively impact on trial quality in regions where resources are scarce.

Methods

1) To compare the methodological quality of all HIV/AIDS RCTs conducted in Africa with a random sample of similar trials conducted in North America; 2) To assess whether location is predictive of trial quality. We searched MEDLINE, EMBASE, CENTRAL and LILACS. Eligible trials were 1) randomized, 2) evaluations of preventive or treatment interventions for HIV/AIDS, 3) reported before 2004, and 4) conducted wholly or partly (if multi-centred) in Africa or North America. We assessed adequacy of random generation, allocation concealment and masking of assessors. Using univariate and multivariate logistic regression analyses we evaluated the association between location (Africa versus North America) and these domains.

Findings

The African search yielded 12,815 records, from which 80 trials were identified. The North American search yielded 13,158 records from which 785 trials were identified and a random sample of 114 selected for analysis. African trials were three times more likely than North American trials to report adequate allocation concealment (OR = 3.24; 95%CI: 1.59 to 6.59; p<0.01) and twice as likely to report adequate generation of the sequence (OR = 2.36; 95%CI: 1.20 to 4.67; p = 0.01), after adjusting for other confounding factors. Additional significant factors positively associated with quality were an a priori sample size power calculation, restricted randomization and inclusion of a flow diagram detailing attrition. We did not detect an association between location and outcome assessor masking.

Conclusions

The higher quality of reporting of methodology in African trials is noteworthy. Most African trials are externally funded, and it is possible that stricter agency requirements when leading trials in other countries and greater experience and training of principal investigators of an international stature, may account for this difference.

Enhancing access to reports of randomized trials published world-wide--the contribution of EMBASE records to the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library

Background

Randomized trials are essential in assessing the effects of healthcare interventions and are a key component in systematic reviews of effectiveness. Searching for reports of randomized trials in databases is problematic due to the absence of appropriate indexing terms until the 1990s and inconsistent application of these indexing terms thereafter.

Objectives

The objectives of this study are to devise a search strategy for identifying reports of randomized trials in EMBASE which are not already indexed as trials in MEDLINE and to make these reports easily accessible by including them in the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, with the permission of Elsevier, the publishers of EMBASE.

Methods

A highly sensitive search strategy was designed for EMBASE based on free-text and thesaurus terms which occurred frequently in the titles, abstracts, EMTREE terms (or some combination of these) of reports of trials indexed in EMBASE. This search strategy was run against EMBASE from 1980 to 2005 (1974 to 2005 for four of the terms) and records retrieved by the search, which were not already indexed as randomized trials in MEDLINE, were downloaded from EMBASE, printed and read. An analysis of the language of publication was conducted for the reports of trials published in 2005 (the most recent year completed at the time of this study).

Results

Twenty-two search terms were used (including nine which were later rejected due to poor cumulative precision). More than a third of a million records were downloaded and scanned and approximately 80,000 reports of trials were identified which were not already indexed as randomized trials in MEDLINE. These are now easily identifiable in CENTRAL, in The Cochrane Library. Cumulative sensitivity ranged from 0.1% to 60% and cumulative precision ranged from 8% to 61%. The truncated term 'random$' identified 60% of the total number of reports of trials but only 35% of the more than 130,000 records retrieved by this term were reports of trials. The language analysis for the sample year 2005 indicated that of the 18,427 reports indexed as randomized trials in MEDLINE, 959 (5%) were in languages other than English. The EMBASE search identified an additional 658 reports in languages other than English, of which the highest number were in Chinese (320).

Conclusion

The results of the search to date have greatly increased access to reports of trials in EMBASE, especially in some languages other than English. The search strategy used was subjectively derived from a small 'gold standard' set of test records and was not validated in an independent test set. We intend to design an objectively-derived validated search strategy using logistic regression based on the frequency of occurrence of terms in the approximately 80,000 reports of randomized trials identified compared with the frequency of these terms across the entire EMBASE database.

Negative pressure wound therapy: potential publication bias caused by lack of access to unpublished study results data

BACKGROUND

Negative pressure wound therapy (NPWT) is widely applied, although the evidence base is weak. Previous reviews on medical interventions have shown that conclusions based on published data alone may no longer hold after consideration of unpublished data. The main objective of this study was to identify unpublished randomised controlled trials (RCTs) on NPWT within the framework of a systematic review.

METHODS

RCTs comparing NPWT with conventional wound therapy were identified using MEDLINE, EMBASE, CINAHL and The Cochrane Library. Every database was searched from inception to May 2005. The search was updated in December 2006. Reference lists of original articles and systematic reviews, as well as congress proceedings and online trial registers, were screened for clues to unpublished RCTs. Manufacturers of NPWT devices and authors of conference abstracts were contacted and asked to provide study information. Trials were considered nonrandomised if concealment of allocation to treatment groups was classified as "inadequate". The study status was classified as "completed", "discontinued", "ongoing" or "unclear". The publication status of completed or discontinued RCTs was classified as "published" if a full-text paper on final study results (completed trials) or interim results (discontinued trials) was available, and "unpublished" if this was not the case. The type of sponsorship was also noted for all trials.

RESULTS

A total of 28 RCTs referring to at least 2755 planned or analysed patients met the inclusion criteria: 13 RCTs had been completed, 6 had been discontinued, 6 were ongoing, and the status of 3 RCTs was unclear. Full-text papers were available on 30% of patients in the 19 completed or discontinued RCTs (495 analysed patients in 10 published RCTs vs. 1154 planned patients in 9 unpublished RCTs). Most information about conference abstracts and unpublished study information referring to trials that were unpublished at the time these documents were generated was obtained from the manufacturer Kinetic Concepts Inc. (KCI) (19 RCTs), followed by The Cochrane Library (18) and a systematic review (15). We were able to obtain some information on the methods of unpublished RCTs, but results data were either not available or requests for results data were not answered; the results of unpublished RCTs could therefore not be considered in the review. One manufacturer, KCI, sponsored the majority of RCTs (19/28; 68%). The sponsorship of the remaining trials was unclear.

CONCLUSION

Multi-source comprehensive searches identify unpublished RCTs. However, lack of access to unpublished study results data raises doubts about the completeness of the evidence base on NPWT.

Poor reporting and inadequate searches were apparent in systematic reviews of adverse effects

OBJECTIVE

Systematic reviews incorporating adverse effects are assuming increasing importance as questions raised extend beyond clinical effectiveness to all effects (beneficial and harmful). The aim of this study was to survey the methods used to identify relevant studies for systematic reviews of adverse effects.

STUDY DESIGN AND SETTING

All records within the Database of Abstracts of Reviews of Effects and the Cochrane Database of Systematic Reviews were scanned for systematic reviews in which the primary outcomes were adverse effects. Two information professionals independently assessed the methods used to identify relevant research as reported in the 277 reviews that met the inclusion criteria.

RESULTS

A major weakness of the reviews was inadequate reporting of the search strategies used. In addition, of the reviews that did report a search strategy, few used the sensitive search strategies recommended for systematic reviews. The majority of reviews did not search more than one or two databases, and few other methods of identifying information were used.

CONCLUSION

This investigation shows the variation in the searching element of systematic reviews of adverse effects and demonstrates that the reporting of the methods used to identify research in such reviews could be vastly improved.

The sensitivity and precision of search terms in Phases I, II and III of the Cochrane Highly Sensitive Search Strategy for identifying reports of randomized trials in medline in a specific area of health care--HIV/AIDS prevention and treatment interventions

OBJECTIVES

To detect term(s) in the Cochrane Highly Sensitive Search Strategy (HSSS) that retain high sensitivity but improve precision in retrieving reports of trials in the PubMed version of medline.

METHODS

Individual terms from the PubMed version of the HSSS were added, term by term, to an African HIV/AIDS strategy to identify reports of trials in medline using PubMed. The titles and abstracts of the records retrieved were read by two handsearchers and checked by a clinical epidemiologist. The sensitivity and precision of each term in the three phases of the HSSS were calculated.

RESULTS

Of 7,719 records retrieved, 285 were identified as reports of trials [204 randomized (RCTs); 81 possibly randomized or quasi-randomized (CCTs)]. Phase III had the highest sensitivity (92%). Overall, precision was very low (3.7%). One term, 'random*[tw]', retrieved all RCTs found by our search and improved precision to 29%. The least sensitive terms, yielding no records, were '(doubl* AND mask*)[tw]' and terms containing 'trebl*' or 'tripl*', except for '(tripl* AND blind*)[tw]'. The highest precision per term was for 'Double-blind Method [MeSH]' (76%).

CONCLUSIONS

To retrieve all RCTs and CCTs found by our search, seven terms are needed but precision remains low (4.3%). Developments in the methods of search strategy design may help to improve precision while retaining high levels of sensitivity by identifying term(s) which occur frequently in relevant records and are the most efficient at discriminating between different study designs.

Searching for CAM Evidence: An Evaluation of Therapy-Specific Search Strategies

OBJECTIVES

The aim of this investigation was to explore the effectiveness of search strategies developed to identify trials of specific complementary therapies in a range of clinical conditions.

DESIGN

All primary studies included in a series of systematic reviews were identified. An analysis of the original source of the study and search term(s) by means of which the study had originally been retrieved was carried out. Each study was then searched for in each of 6 databases (AMED, Cochrane CENTRAL, MEDLINE/PubMed, EMBASE, CINAHL, PsycINFO). The proportion of studies located on each database was assessed and the indexing terms identified for each therapy were compared against the original search strategies.

RESULTS

A total of 127 primary studies were identified from 35 systematic reviews. The number of studies on each therapy varied, but Cochrane CENTRAL listed the highest proportion for all therapies. No database listed all studies, and at least one unique study was listed on all databases except MEDLINE, whereas several studies were not found on any of the databases. Index terms were effective in locating studies on acupuncture, individual herbs, hypnosis, massage, and yoga. For the remaining therapies, use of text word search terms was important and particularly so for homeopathy, meditation, and reflexology. Variation in terminology for most of the therapies was encountered.

CONCLUSIONS

The small numbers of studies preclude firm recommendations, but several potential challenges in searching for complementary and alternative medicine (CAM) trials are highlighted. The findings suggest that a range of different sources is required for identifying relevant studies, particularly for certain therapies. The development of an optimum generic search strategy for each therapy is hampered by the variation in indexing of CAM studies. Possible optimum strategies are presented as a basis for discussion, and further testing of the effectiveness of these strategies is now a priority.