How effects on health equity are assessed in systematic reviews of interventions

BACKGROUND

Enhancing health equity has now achieved international political importance with endorsement from the World Health Assembly in 2009.  The failure of systematic reviews to consider effects on health equity is cited by decision-makers as a limitation to their ability to inform policy and program decisions. 

OBJECTIVES

To systematically review methods to assess effects on health equity in systematic reviews of effectiveness.

SEARCH STRATEGY

We searched the following databases up to July 2 2010: MEDLINE, PsychINFO, the Cochrane Methodology Register, CINAHL, Education Resources Information Center, Education Abstracts, Criminal Justice Abstracts, Index to Legal Periodicals, PAIS International, Social Services Abstracts, Sociological Abstracts, Digital Dissertations and the Health Technology Assessment Database. We searched SCOPUS to identify articles that cited any of the included studies on October 7 2010.

SELECTION CRITERIA

We included empirical studies of cohorts of systematic reviews that assessed methods for measuring effects on health inequalities.

DATA COLLECTION AND ANALYSIS

Data were extracted using a pre-tested form by two independent reviewers. Risk of bias was appraised for included studies according to the potential for bias in selection and detection of systematic reviews. 

MAIN RESULTS

Thirty-four methodological studies were included.  The methods used by these included studies were: 1) Targeted approaches (n=22); 2) gap approaches (n=12) and gradient approach (n=1).  Gender or sex was assessed in eight out of 34 studies, socioeconomic status in ten studies, race/ethnicity in seven studies, age in seven studies, low and middle income countries in 14 studies, and two studies assessed multiple factors across health inequity may exist.Only three studies provided a definition of health equity. Four methodological approaches to assessing effects on health equity were identified: 1) descriptive assessment of reporting and analysis in systematic reviews (all 34 studies used a type of descriptive method); 2) descriptive assessment of reporting and analysis in original trials (12/34 studies); 3) analytic approaches (10/34 studies); and 4) applicability assessment (11/34 studies). Both analytic and applicability approaches were not reported transparently nor in sufficient detail to judge their credibility.

AUTHORS' CONCLUSIONS

There is a need for improvement in conceptual clarity about the definition of health equity, describing sufficient detail about analytic approaches (including subgroup analyses) and transparent reporting of judgments required for applicability assessments in order to assess and report effects on health equity in systematic reviews.

Interventions to improve question formulation in professional practice and self-directed learning

BACKGROUND

Formulating questions is fundamental to the daily life of a healthcare worker and is a defining characteristic of professional competence and meaningful learning. With high expectations for healthcare providers to remain up-to-date with current evidence and the movement towards formalizing reflective practice as part of physician revalidation, it is important that curricula developed for improving the ability to formulate well-constructed questions are based on the best evidence.

OBJECTIVES

To assess the effectiveness of interventions for increasing the frequency and quality of questions formulated by healthcare providers in practice and the context of self-directed learning.

SEARCH STRATEGY

We obtained studies from searches of electronic bibliographic databases, and supplemented these with handsearching, checking reference lists, and consultation with experts.

SELECTION CRITERIA

We considered published and unpublished randomized controlled trials (RCTs), controlled clinical trials (CCTs), interrupted time-series (ITS), and controlled before-after (CBA) studies of any language examining interventions for increasing the quality and frequency of questions formulated by health professionals involved with direct patient care.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook all relevancy screening and 'Risk of bias' assessment in duplicate. Intervention characteristics, follow-up intervals, and measurement outcomes were diverse and precluded quantitative analysis. We have summarized data descriptively.

MAIN RESULTS

Searches identified four studies examining interventions to improve question formulation in healthcare professionals. Interventions were mostly multi-component, limited within the context of EBM and primarily in physician and resident populations. We did not identify studies examining changes in frequency of questions formulated or those within the context of reflection. Risk of bias was generally rated to be 'high risk'. Three of the four studies showed improvements in question formulation in physicians, residents, or mixed allied health populations in the short- to moderate term follow up. Only one study examined sustainability of effects at one year and reported that skills had eroded over time.

AUTHORS' CONCLUSIONS

Evidence from our review suggests that interventions to increase the quality of questions formulated in practice produce mixed results at both short- (immediately following intervention), and moderate-term follow up (up to nine months), comparatively. Although three studies reported effectiveness estimates of an educational intervention for increasing the quality of question formulation within the short term, only one study examined the effectiveness in the longer term (one year) and revealed that search skills had eroded over time. Data suggests that sustainability of effects from educational interventions for question formulation are unknown.

An Evidence Based Checklist for the Peer Review of Electronic Search Strategies (PRESS EBC)

No abstract.

Electronic search strategies to identify reports of cluster randomized trials in MEDLINE: low precision will improve with adherence to reporting standards

Background

Cluster randomized trials (CRTs) present unique methodological and ethical challenges. Researchers conducting systematic reviews of CRTs (e.g., addressing methodological or ethical issues) require efficient electronic search strategies (filters or hedges) to identify trials in electronic databases such as MEDLINE. According to the CONSORT statement extension to CRTs, the clustered design should be clearly identified in titles or abstracts; however, variability in terminology may make electronic identification challenging. Our objectives were to (a) evaluate sensitivity ("recall") and precision of a well-known electronic search strategy ("randomized controlled trial" as publication type) with respect to identifying CRTs, (b) evaluate the feasibility of new search strategies targeted specifically at CRTs, and (c) determine whether CRTs are appropriately identified in titles or abstracts of reports and whether there has been improvement over time.

Methods

We manually examined a wide range of health journals to identify a gold standard set of CRTs. Search strategies were evaluated against the gold standard set, as well as an independent set of CRTs included in previous systematic reviews.

Results

The existing strategy (randomized controlled trial.pt) is sensitive (93.8%) for identifying CRTs, but has relatively low precision (9%, number needed to read 11); the number needed to read can be halved to 5 (precision 18.4%) by combining with cluster design-related terms using the Boolean operator AND; combining with the Boolean operator OR maximizes sensitivity (99.4%) but would require 28.6 citations read to identify one CRT. Only about 50% of CRTs are clearly identified as cluster randomized in titles or abstracts; approximately 25% can be identified based on the reported units of randomization but are not amenable to electronic searching; the remaining 25% cannot be identified except through manual inspection of the full-text article. The proportion of trials clearly identified has increased from 28% between the years 2000-2003, to 60% between 2004-2007 (absolute increase 32%, 95% CI 17 to 47%).

Conclusions

CRTs should include the phrase "cluster randomized trial" in titles or abstracts; this will facilitate more accurate indexing of the publication type by reviewers at the National Library of Medicine, and efficient textword retrieval of the subset employing cluster randomization.

Neonatal respiratory failure due to a novel mutation in the surfactant protein C gene

A full-term infant developed respiratory distress immediately after birth, requiring a prolonged course of extra-corporeal membrane oxygenation, followed by high-frequency ventilation. She was unable to wean off mechanical ventilation, required tracheostomy, and ultimately lung transplantation. A novel mutation in the surfactant C protein gene was identified as the cause of her lung disease.

Barriers to the effective treatment and prevention of malaria in Africa: A systematic review of qualitative studies

BACKGROUND

In Africa, an estimated 300-500 million cases of malaria occur each year resulting in approximately 1 million deaths. More than 90% of these are in children under 5 years of age. To identify commonly held beliefs about malaria that might present barriers to its successful treatment and prevention, we conducted a systematic review of qualitative studies examining beliefs and practices concerning malaria in sub-Saharan African countries.

METHODS

We searched Medline and Scopus (1966-2009) and identified 39 studies that employed qualitative methods (focus groups and interviews) to examine the knowledge, attitudes, and practices of people living in African countries where malaria is endemic. Data were extracted relating to study characteristics, and themes pertaining to barriers to malaria treatment and prevention.

RESULTS

The majority of studies were conducted in rural areas, and focused mostly or entirely on children. Major barriers to prevention reported included a lack of understanding of the cause and transmission of malaria (29/39), the belief that malaria cannot be prevented (7/39), and the use of ineffective prevention measures (12/39). Thirty-seven of 39 articles identified barriers to malaria treatment, including concerns about the safety and efficacy of conventional medicines (15/39), logistical obstacles, and reliance on traditional remedies. Specific barriers to the treatment of childhood malaria identified included the belief that a child with convulsions could die if given an injection or taken to hospital (10/39).

CONCLUSION

These findings suggest that large-scale malaria prevention and treatment programs must account for the social and cultural contexts in which they are deployed. Further quantitative research should be undertaken to more precisely measure the impact of the themes uncovered by this exploratory analysis.

Improving healthcare consumer effectiveness: an Animated, Self-serve, Web-based Research Tool (ANSWER) for people with early rheumatoid arthritis

BACKGROUND

People with rheumatoid arthritis (RA) should use DMARDs (disease-modifying anti-rheumatic drugs) within the first three months of symptoms in order to prevent irreversible joint damage. However, recent studies report the delay in DMARD use ranges from 6.5 months to 11.5 months in Canada. While most health service delivery interventions are designed to improve the family physician's ability to refer to a rheumatologist and prescribe treatments, relatively little has been done to improve the delivery of credible, relevant, and user-friendly information for individuals to make treatment decisions. To address this care gap, the Animated, Self-serve, Web-based Research Tool (ANSWER) will be developed and evaluated to assist people in making decisions about the use of methotrexate, a type of DMARD. The objectives of this project are: 1) to develop ANSWER for people with early RA; and 2) to assess the extent to which ANSWER reduces people's decisional conflict about the use of methotrexate, improves their knowledge about RA, and improves their skills of being 'effective healthcare consumers'.

METHODS/DESIGN

Consistent with the International Patient Decision Aid Standards, the development process of ANSWER will involve: 1.) creating a storyline and scripts based on the best evidence on the use of methotrexate and other management options in RA, and the contextual factors that affect a patient's decision to use a treatment as found in ERAHSE; 2.) using an interactive design methodology to create, test, analyze and refine the ANSWER prototype; 3.) testing the content and user interface with health professionals and patients; and 4.) conducting a pilot study with 51 patients, who are diagnosed with RA in the past 12 months, to assess the extent to which ANSWER improves the quality of their decisions, knowledge and skills in being effective consumers.

DISCUSSION

We envision that the ANSWER will help accelerate the dissemination of knowledge and skills necessary for people with early RA to make informed choices about treatment and to manage their health. The latest in animation and online technology will ensure ANSWER fills a knowledge translation gap, focusing on the next generation of people living with RA.

Electronic retrieval of health information by healthcare providers to improve practice and patient care

BACKGROUND

The movement towards evidence-based practice makes explicit the need for access to current best evidence to improve health. Advances in electronic technologies have made health information more available, but does availability affect the rate of use of evidence in practice?

OBJECTIVES

To assess the effectiveness of interventions intended to provide electronic retrieval (access to information) to health information by healthcare providers to improve practice and patient care.

SEARCH STRATEGY

We obtained studies from computerized searches of multiple electronic bibliographic databases, supplemented by checking reference lists, and consultation with experts.

SELECTION CRITERIA

Randomized controlled trials (RCTs) including cluster randomized trials (CRCTs), controlled clinical trials (CCT), and interrupted time series analyses (ITS) of any language publication status examining interventions of effectiveness of electronic retrieval of health information by healthcare providers.

DATA COLLECTION AND ANALYSIS

Duplicate relevancy screening of searches, data abstraction and risk of bias assessment was undertaken.

MAIN RESULTS

We found two studies that examined this question. Neither study found any changes in professional behavior following an intervention that facilitated electronic retrieval of health information. There was some evidence of improvements in knowledge about the electronic sources of information reported in one study. Neither study assessed changes in patient outcomes or the costs of provision of the electronic resource and the implementation of the recommended evidence-based practices.

AUTHORS' CONCLUSIONS

Overall there was insufficient evidence to support or refute the use of electronic retrieval of healthcare information by healthcare providers to improve practice and patient care.

Age, gender, and race/ethnic differences in total body and subregional bone density

SUMMARY

Total body bone density of adults from National Health and Nutrition Examination Survey (NHANES) 1999-2004 differed as expected for some groups (men>women and blacks>whites) but not others (whites>Mexican Americans). Cross-sectional age patterns in bone mineral density (BMD) of older adults differed at skeletal sites that varied by degree of weight-bearing.

INTRODUCTION

Total body dual-energy X-ray absorptiometry (DXA) data offer the opportunity to compare bone density of demographic groups across the entire skeleton.

METHODS

The present study uses total body DXA data (Hologic QDR 4500A, Hologic, Bedford MA, USA) from the NHANES 1999-2004 to examine BMD of the total body and selected skeletal subregions in a wide age range of adult men and women from three race/ethnic groups. Total body, lumbar spine, pelvis, right leg, and left arm BMD and lean mass from 13,091 adults aged 20 years and older were used. The subregions were chosen to represent sites with different degrees of weight-bearing.

RESULTS

Mean BMD varied in expected ways for some demographic characteristics (men>women and non-Hispanic blacks>non-Hispanic whites) but not others (non-Hispanic whites>Mexican Americans). Differences in age patterns in BMD also emerged for some characteristics (sex) but not others (race/ethnicity). Differences in cross-sectional age patterns in BMD and lean mass by degree of weight-bearing in older adults were observed for the pelvis, leg, and arm.

CONCLUSION

This information may be useful for generating hypotheses about age, race, and sex differences in fracture risk in the population.

Risk factors for low BMD in healthy men age 50 years or older: a systematic review

SUMMARY

In this systematic review, we summarize risk factors for low bone mineral density and bone loss in healthy men age 50 years or older. Consistent risk factors were: age, smoking, low weight, physical/functional limitations, and previous fracture. Data specific to men has clinical and policy implications.

INTRODUCTION

Osteoporosis is a significant health care problem in men as well as women, yet the majority of evidence on diagnosis and management of osteoporosis is focused on postmenopausal women. The objective of this systematic review is to examine risk factors for low bone mineral density (BMD) and bone loss in healthy men age 50 years or older.

MATERIALS AND METHODS

A systematic search for observational studies was conducted in MEDLINE, Cochrane Database of Systematic Reviews, DARE, CENTRAL, CINAHL and Embase, Health STAR. The three main search concepts were bone density, densitometry, and risk factors. Trained reviewers assessed articles using a priori criteria.

RESULTS

Of 642 screened abstracts, 299 articles required a full review, and 25 remained in the final assessment. Consistent risk factors for low BMD/bone loss were: advancing age, smoking, and low weight/weight loss. Although less evidence was available, physical/functional limitations and prevalent fracture (after age 50) were also associated with low BMD/bone loss. The evidence was inconsistent or weak for physical activity, alcohol consumption, calcium intake, muscle strength, family history of fracture/osteoporosis, and height/height loss.

CONCLUSION

In this systematic review, we identified several risk factors for low BMD/bone loss in men that are measurable in primary practice.

An evidence-based practice guideline for the peer review of electronic search strategies

OBJECTIVE

Complex and highly sensitive electronic literature search strategies are required for systematic reviews; however, no guidelines exist for their peer review. Poor searches may fail to identify existing evidence because of inadequate recall (sensitivity) or increase the resource requirements of reviews as a result of inadequate precision. Our objective was to create an annotated checklist for electronic search strategy peer review.

STUDY DESIGN

A systematic review of the library and information retrieval literature for important elements in electronic search strategies was conducted, along with a survey of individuals experienced in systematic review searching.

RESULTS

Six elements with a strong consensus as to their importance in peer review were accurate translation of the research question into search concepts, correct choice of Boolean operators and of line numbers, adequate translation of the search strategy for each database, inclusion of relevant subject headings, and absence of spelling errors. Seven additional elements had partial support and are included in this guideline.

CONCLUSION

This evidence-based guideline facilitates the improvement of search quality through peer review, and thus the improvement in quality of systematic reviews. It is relevant for librarians/information specialists, journal editors, developers of knowledge translation tools, research organizations, and funding bodies.

Risk factors for low bone mass in healthy 40-60 year old women: a systematic review of the literature

Based on a systematic review of the literature, only low body weight and menopausal status can be considered with confidence, as important risk factors for low BMD in healthy 40-60 year old women. The use of body weight to identify high risk women may reduce unnecessary BMD testing in this age group.

INTRODUCTION

BMD testing of perimenopausal women is increasing but may be unnecessary as fracture risk is low. Appropriate assessment among younger women requires identification of risk factors for low BMD specific to this population.

METHODS

We conducted a systematic literature review of risk factors for low BMD in healthy women aged 40-60 years. Articles were retrieved from six databases and reviewed for eligibility and methodological quality. A grade for overall strength of evidence for each risk factor was assigned.

RESULTS

There was good evidence that low body weight and post-menopausal status are risk factors for low BMD. There was good or fair evidence that alcohol and caffeine intake, and reproductive history are not risk factors. There was inconsistent or insufficient evidence for the effect of calcium intake, physical activity, smoking, age at menarche, history of amenorrhea, family history of OP, race and current age on BMD.

CONCLUSIONS

Based on current evidence in Caucasians, we suggest that, in healthy women aged 40-60 years, only those with a low body weight (< 70 kg) be selected for BMD testing. Further research is necessary to determine optimal race-specific discriminatory weight cut-offs and to evaluate the risk factors for which there was inconclusive evidence.

Just-in-time information improved decision-making in primary care: a randomized controlled trial

BACKGROUND

The "Just-in-time Information" (JIT) librarian consultation service was designed to provide rapid information to answer primary care clinical questions during patient hours. This study evaluated whether information provided by librarians to answer clinical questions positively impacted time, decision-making, cost savings and satisfaction.

METHODS AND FINDING

A randomized controlled trial (RCT) was conducted between October 2005 and April 2006. A total of 1,889 questions were sent to the service by 88 participants. The object of the randomization was a clinical question. Each participant had clinical questions randomly allocated to both intervention (librarian information) and control (no librarian information) groups. Participants were trained to send clinical questions via a hand-held device. The impact of the information provided by the service (or not provided by the service), additional resources and time required for both groups was assessed using a survey sent 24 hours after a question was submitted. The average time for JIT librarians to respond to all questions was 13.68 minutes/question (95% CI, 13.38 to 13.98). The average time for participants to respond their control questions was 20.29 minutes/question (95% CI, 18.72 to 21.86). Using an impact assessment scale rating cognitive impact, participants rated 62.9% of information provided to intervention group questions as having a highly positive cognitive impact. They rated 14.8% of their own answers to control question as having a highly positive cognitive impact, 44.9% has having a negative cognitive impact, and 24.8% with no cognitive impact at all. In an exit survey measuring satisfaction, 86% (62/72 responses) of participants scored the service as having a positive impact on care and 72% (52/72) indicated that they would use the service frequently if it were continued.

CONCLUSIONS

In this study, providing timely information to clinical questions had a highly positive impact on decision-making and a high approval rating from participants. Using a librarian to respond to clinical questions may allow primary care professionals to have more time in their day, thus potentially increasing patient access to care. Such services may reduce costs through decreasing the need for referrals, further tests, and other courses of action.

TRIAL REGISTRATION

Controlled-Trials.com ISRCTN96823810.

Nausea and vomiting in HIV: a symptom review

Nausea and vomiting are two of the most common symptoms experienced by those with HIV. While the causes are most commonly attributed to medication side effects, infectious causes, gastroparesis and psychosomatic, therapy aimed at controlling symptoms has not been well studied. Since nausea and vomiting have been identified as the most common cause of discontinuation of highly active antiretroviral therapy (HAART) therapy, and due to the extensive morbidity associated with these symptoms, we sought to review and discuss causes and management of these symptoms in HIV-infected patients and demonstrate the need for further research in this area. Such studies could include investigation into the prophylactic use of antiemetics with initiation or modification of HAART therapy to monitor patient compliance. In addition, anticipatory nausea and vomiting should be further studied, as it could prove to be quite prevalent, as in cancer patients.

Tetanus antibody protection among HIV-infected US-born patients and immigrants

INTRODUCTION

Public health initiatives to immunize children and adults have effectively reduced the number of tetanus cases in the USA. However, in the Third National Health and Nutrition Examination Survey (NHANES III), immigrants from Mexico had a 67% nonprotective anti-tetanus antibody (ATA) level. Less work has been conducted among other vulnerable populations such as human immunodeficiency virus (HIV)-infected patients. The objective of this study was to measure ATA levels among the HIV immigrant population compared with US-born HIV-infected patients.

METHODS

A convenience sample of 158 HIV-infected individuals was recruited to determine the levels of ATA. A nonprotective level of ATA was defined as below 0.15 IU/ml.

RESULTS

Among the HIV-infected patients, 72% (114/158) were born in the USA. A total of 17% (27/158) lacked protective levels of ATA. A total of 6.1% (7/114) of those born in the USA lacked protection, compared to 45% (20/44) born outside the USA (p < 0.0001).

CONCLUSION

The results illustrate that the country of birth is an important predictor of ATA protection, even among HIV-infected patients.

No consensus exists on search reporting methods for systematic reviews

OBJECTIVES

The reporting of the search methods used in systematic reviews has implications for how systematic reviews are critically appraised, their reproducibility and how easily they may be updated. The objective of this paper was to identify validated or evaluated search reporting instruments used in reporting systematic review searches and to compare reported and recommended searching practices.

STUDY DESIGN AND SETTING

This cohort study was a systematic review. The search strategy to identify instruments addressing the reporting of search strategies was developed first in the Library & Information Science Abstracts (LISAs) database and then adapted for MEDLINE and five additional databases. Additional instruments were identified through experts. Current reporting practice data were analyzed from a cohort of 297 recent systematic reviews.

RESULTS

Of the 11 instruments examined, 7 cited supporting evidence but only 4 were validated. Eighteen different reporting items were identified but only one item, "databases used," appeared in all instruments. There was a trend toward including more items in more recent instruments (r=0.41). Current search reporting practices ranged from a high of 98.7% for databases used to a low of 11.4% for qualifications of the searcher.

CONCLUSIONS

There is no clear consensus regarding optimum reporting of systematic review search methods and commonly recommended items show suboptimal reporting.

Surveillance search techniques identified the need to update systematic reviews

OBJECTIVE

This article reports on literature surveillance methods to identify new evidence eligible for updating systematic reviews.

STUDY DESIGN AND SETTING

Five surveillance search approaches are tested in the context of identifying studies that would signal major or invalidating new evidence for existing systematic reviews of health care interventions. Recall for each search approach was assessed as proportion of a composite yield of relevant studies across all search approaches that were identified by that approach. Screening burden was the number of studies that would need to be reviewed to identify the evidence that would necessitate updating.

RESULTS

Searches were tested in a cohort of 77 systematic reviews. No one method yielded consistently high recall of relevant new evidence, so combinations of the strategies were examined. A search algorithm based on PubMed's related article search in combination with a subject searching using clinical queries was the most effective combination, retrieving all relevant new records in 68 cases. Screening burden was a median of 71 new records per review (inter-quartile range: 42-161).

CONCLUSION

Surveillance for emerging evidence that signals the need to update systematic reviews is feasible using a combination of subject searching and searching based on the PubMed's related article function.

Clinical trial: an efficacy evaluation of reduced bisacodyl given as part of a polyethylene glycol electrolyte solution preparation prior to colonoscopy

BACKGROUND

In an attempt to further improve patient preparation experience with reduced volume gut lavage solutions using 2-L sulphate-free electrolyte lavage solution plus 20-mg bisacodyl (HalfLytely with Bisacodyl Tablets Bowel Prep Kit, Braintree Laboratories, Inc., Braintree, MA, USA), a low bisacodyl dose preparation was developed using 10 mg bisacodyl.

AIM

To compare preparation methods using the 10- or 20-mg bisacodyl with 2-L sulphate-free electrolyte lavage method.

METHODS

At 10 US centres, 455 patients undergoing colonoscopy for routine clinical indications were equally randomized to receive 10- or 20-mg bisacodyl with 2-L sulphate-free electrolyte lavage method. Colonoscopists rated the efficacy of colon cleansing, blinded to the preparation assignment.

RESULTS

Physician assessment of colon cleansing showed no difference between those randomized to receive the 10- or 20-mg bisacodyl preparations (P = 0.52). The 10-mg preparation had lower symptom scores for cramping (P < 0.001) and overall discomfort (P = 0.001). Other reported adverse experiences were few, mild and not different between groups.

CONCLUSION

Two-litre sulphate-free electrolyte lavage method solution with 10-mg bisacodyl is as effective as the 20-mg bisacodyl preparation for cleansing the colon prior to colonoscopy. The 10-mg bisacodyl regimen has an improved safety profile, with significantly reduced cramping, nausea and overall discomfort.

Non-Fourier motion analysis

It has been realized for some time that the visual system performs at least two general sorts of motion processing. First-order motion processing applies some variant of standard motion analysis (i.e. spatiotemporal Fourier energy analysis) directly to stimulus luminance, whereas second-order motion processing applies standard motion analysis to one or another grossly non-linear transformation of stimulus luminance. We have developed a method for disentangling the different sorts of mechanisms that may operate in human vision to detect second-order motion. This method hinges on an empirical condition called transition invariance that may or may not be satisfied by a family psi of textures. Any failure of this condition indicates that more than one mechanism is involved in detecting the motion of stimuli composed of the textures in psi. We have shown that the family of sinusoidal gratings oriented orthogonally to the direction of motion and varying in contrast and spatial frequency is transition invariant. We modelled the results in terms of a single-channel motion computation. We have new results indicating that a specific class of textures differing in texture element density and texture element contrast decisively fails the test of transition invariance. These findings suggest that in addition to the single second-order motion channel required by our earlier results there exists at least one other second-order motion channel. We argue that the preprocessing transformation used by this channel is a pointwise non-linearity that maps stimulus contrasts of absolute value less than some relatively high threshold tau onto 0, but increases with magnitude of c-tau for contrasts. c of absolute value greater than tau.