Christine Clar

Screening for hyperglycaemia in pregnancy: A rapid update for the National Screening Committee

BACKGROUND Screening for gestational diabetes has long been a controversial topic. A previous Health Technology Assessment (HTA) report reviewed literature on screening for gestational diabetes mellitus (GDM) and assessed the case for screening against the criteria set by the National Screening Committee. OBJECTIVE To update a previous HTA report which reviewed the literature on screening for GDM by examining evidence that has emerged since that last report, including the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS), the Maternal and Fetal Medicine Units Network (MFMUN) trial and the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study. To review data on recent trends in maternal age at birth and on the prevalence of overweight and obesity and the effect on prevalence of GDM. DATA SOURCES A systematic review and meta-analysis of the literature was carried out. The bibliographic databases used were MEDLINE (1996 to January 2009), EMBASE (1996 to December 2009), the Cochrane Library 2008 issue 4, the Centre for Reviews and Dissemination database and the Web of Science. REVIEW METHODS For the review of treatment with oral drugs versus insulin, a full systematic review and meta-analysis was carried out. The results of the ACHOIS, MFMUN and HAPO studies were summarised and their implications discussed. Findings of a selection of other recent studies, relevant to the continuum issue, were summarised. Some recent screening studies were reviewed, including a particular focus on studies of screening earlier in pregnancy. RESULTS The HAPO results showed a linear relationship between plasma glucose and adverse outcomes - there is a continuum of risk with no clear threshold which could divide women into those with gestational diabetes and those without. There was good evidence from trials and the meta-analysis that women who fail to control hyperglycaemic in pregnancy on lifestyle measures alone can be safely and effectively be treated with oral agents, metformin or glibenclamide, rather than going directly to insulin. Evidence showed few differences in results between glibenclamide and insulin and metformin and insulin. The exceptions were that there was less maternal hypoglycaemia with glibenclamide, but less neonatal hypoglycaemia and lower birthweight with insulin, and there was less maternal weight gain with metformin. The ACHOIS and MFMUN trials showed reductions in perinatal complications among infants born to mothers who were provided with more intensive dietary advice, blood glucose monitoring and insulin when required. The HAPO study demonstrated adverse outcomes over a much wider range of blood glucose (BG) than the traditional definition of GDM. In the HAPO study, no one measure of BG came out as being clearly the best, although fasting plasma glucose (FPG) was as good as any, and had advantages of being more convenient than an oral glucose tolerance test (OGTT), but correlations between fasting and post-load levels were quite poor. Two screening strategies dominated; (1) selection by the American Diabetes Association criteria followed by the 75-g OGTT [incremental cost-effectiveness ratio (ICER) 3678 pounds], and (2) selection by high-risk ethnicity followed by the 75-g OGTT (ICER 21,739 pounds). Studies indicated that costs are about 1833 pounds higher for pregnancies complicated by gestational diabetes, suggesting that prevention would be worthwhile. LIMITATIONS Not all of the HAPO results have been published, and none of the reviewed economic studies resolved the most difficult issue - at what level of BG does intervention become cost-effective? CONCLUSIONS The evidence base has improved since the last HTA review in 2002. There is now good evidence for treatment of oral drugs instead of insulin and it looks increasingly as if FPG could be the test of choice. However some key uncertainties remain to be resolved, which can be done by further analysis of the already collected HAPO data and by using the UK model used in developing the NICE guidelines to assess the cost-effectiveness of intervention in each of the seven HAPO categories.

Self-monitoring of blood glucose in type 2 diabetes: systematic review

OBJECTIVES To examine whether or not self-monitoring of blood glucose (SMBG) is worthwhile, in terms of glycaemic control, hypoglycaemia, quality of life (QoL) and cost per quality-adjusted life-year (QALY), in people with type 2 diabetes (T2DM) who were not treated with insulin or who were on basal insulin in combination with oral agents. DATA SOURCES Literature searched included systematic reviews published since 1996, and a systematic review and meta-analyses of randomised controlled trials (RCTs) identified from the reviews, and from searches for more recent trials, along with review of qualitative and economic studies. Search strategies were limited to the English language and to articles published since 1996, and included: databases searched from 1996 to April 2009 - The Cochrane Library, MEDLINE, EMBASE, PsycINFO, Web of Science - limited to meeting abstracts; and websites. REVIEW METHODS The intervention was self-testing of blood glucose with a meter and test strips. Studies included adult patients with T2DM on any oral treatment or combination of regimens, including lifestyle, oral agents or once-daily basal insulin. Existing systematic reviews of SMBG were summarised and results compared. Evidence synthesis of all of the studies meeting the inclusion criteria was carried out using a narrative review. Data were analysed by outcome and subgroups. HbA1c data from RCTs were summarised using a meta-analysis. Heterogeneity was calculated using the chi-squared and I2 methods. The following analyses were carried out: SMBG compared to self-monitoring of urine glucose, SMBG versus no SMBG, more intensive SMBG versus less intensive SMBG, and more intensive SMBG versus no SMBG. Available qualitative data gained from in-depth interview studies, repeated interviews, and questionnaire and survey data were summarised. RESULTS The review identified 30 RCTs, although few were of high quality. Ten trials comparing SMBG with no SMBG showed statistically significant reduction in HbA1C of 0.21%, which may not be considered clinically significant. A similar, though not statistically significant difference, was shown where SMBG with education was compared to SMBG without education or feedback. RCTs showed no consistent effect on hypoglycaemic episodes and no impact on medication changes. Review of cost-effectiveness studies showed that costs of SMBG per annum vary considerably (10-259 pounds). Although some studies assert that SMBG may lead to savings in health-care costs which may offset the costs of testing, the best analysis to date (DiGEM - Diabetes Glycaemic Education and Monitoring) concluded that SMBG was not cost-effective. Qualitative studies revealed that there was a lack of education in how to interpret and use the data from SMBG, and that failure to act on the results was common. CONCLUSIONS The evidence suggested that SMBG is of limited clinical effectiveness in improving glycaemic control in people with T2DM on oral agents, or diet alone, and is therefore unlikely to be cost-effective. SMBG may lead to improved glycaemic control only in the context of appropriate education - both for patients and health-care professionals - on how to respond to the data, in terms of lifestyle and treatment adjustment. Also, SMBG may be more effective if patients are able to self-adjust drug treatment. Further research is required on the type of education and feedback that are most helpful, characteristics of patients benefiting most from SMBG, optimal timing and frequency of SMBG, and the circumstances under which SMBG causes anxiety and/or depression.

Systematic review of SGLT2 receptor inhibitors in dual or triple therapy in type 2 diabetes

Background Despite the number of medications for type 2 diabetes, many people with the condition do not achieve good glycaemic control. Some existing glucose-lowering agents have adverse effects such as weight gain or hypoglycaemia. Type 2 diabetes tends to be a progressive disease, and most patients require treatment with combinations of glucose-lowering agents. The sodium glucose co-transporter 2 (SGLT2) receptor inhibitors are a new class of glucose-lowering agents. Objective To assess the clinical effectiveness and safety of the SGLT2 receptor inhibitors in dual or triple therapy in type 2 diabetes. Data sources MEDLINE, Embase, Cochrane Library (all sections); Science Citation Index; trial registries; conference abstracts; drug regulatory authorities; bibliographies of retrieved papers. Inclusion criteria Randomised controlled trials of SGLT2 receptor inhibitors compared with placebo or active comparator in type 2 diabetes in dual or combination therapy. Methods Systematic review. Quality assessment used the Cochrane risk of bias score. Results Seven trials, published in full, assessed dapagliflozin and one assessed canagliflozin. Trial quality appeared good. Dapagliflozin 10 mg reduced HbA1c by −0.54% (weighted mean differences (WMD), 95% CI −0.67 to −0.40) compared to placebo, but there was no difference compared to glipizide. Canagliflozin reduced HbA1c slightly more than sitagliptin (up to −0.21% vs sitagliptin). Both dapagliflozin and canagliflozin led to weight loss (dapagliflozin WMD −1.81 kg (95% CI −2.04 to −1.57), canagliflozin up to −2.3 kg compared to placebo). Limitations Long-term trial extensions suggested that effects were maintained over time. Data on canagliflozin are currently available from only one paper. Costs of the drugs are not known so cost-effectiveness cannot be assessed. More data on safety are needed, with the Food and Drug Administration having concerns about breast and bladder cancers. Conclusions Dapagliflozin appears effective in reducing HbA1c and weight in type 2 diabetes, although more safety data are needed.

Faecal calprotectin testing for differentiating amongst inflammatory and non-inflammatory bowel diseases: systematic review and economic evaluation.

BACKGROUND Irritable bowel syndrome (IBS) is common, and causes pain, bloating and diarrhoea and/or constipation. It is a troublesome condition that reduces the quality of life but causes no permanent damage. Inflammatory bowel disease (IBD) comprises mainly ulcerative colitis (UC) and Crohns disease (CD). Both cause serious complications and may lead to sections of the bowel having to be removed, although this is more common with CD. The presenting symptoms of IBS and IBD can be similar. Distinguishing them on clinical signs and symptoms can be difficult. Until recently, colonoscopy was often required to rule out IBD. In younger people, > 60% of colonoscopies showed no abnormality. Faecal calprotectin (FC) is a protein released by the white blood cells, neutrophils, found in inflamed areas of the bowel in IBD. Determining the level of FC in stool samples may help distinguish IBS from IBD. OBJECTIVE To review the value of FC for distinguishing between IBD and non-IBD. DATA SOURCES Sources included MEDLINE, EMBASE, The Cochrane Library, Web of Science, websites of journals and the European Crohns and Colitis Organisation (conference abstracts 2012 and 2013), and contact with experts. REVIEW METHODS Systematic review and economic modelling. Review Manager (RevMan) version 5.2 (The Cochrane Collaboration, The Nordic Cochrane Centre, Copenhagen, Denmark) was used for most analysis, with statistical analyses done in Stata version 12 (StataCorp LP, College Station, TX, USA). Forest plots and receiver operating characteristic curves were produced. Quality Assessment of Diagnostic Accuracy Studies was used for quality assessment. Economic modelling was done in Microsoft Excel 2010 (Microsoft Corporation, Redmond, WA, USA). LIMITATIONS Studies were often small, most used only one calprotectin cut-off level, and nearly all came from secondary care populations. RESULTS Twenty-eight studies provided data for 2 × 2 tables and were included in meta-analyses, with seven in the most important comparison in adults (IBS vs. IBD) and eight in the key comparison in paediatrics (IBD vs. non-IBD). Most studies used laboratory enzyme-linked immunosorbent assay (ELISA) tests. For distinguishing between IBD and IBS in adults, these gave pooled sensitivity of 93% and specificity of 94% at FC cut-off level of 50 µg/g. Sensitivities at that cut-off ranged from 83% to 100%, and specificities from 60% to 100%. For distinguishing between IBD and non-IBD in paediatric populations with ELISA tests, sensitivities ranged from 95% to 100% at cut-off of 50 µg/g and specificities of 44-93%. Few studies used point-of-care testing but that seemed as reliable as ELISA, though perhaps less specific. The evidence did not provide any grounds for preferring one test over others on clinical effectiveness grounds. FC testing in primary care could reduce the need for referral and colonoscopies. Any quality-adjusted life-year gains are likely to be small because of the low prevalence of IBD and the high sensitivities of all of the tests, resulting in few false negatives with IBD. However, considerable savings could accrue. Areas of uncertainty include the optimum management of people with borderline results (50-150 µg/g), most of whom do not have IBD. Repeat testing may be appropriate before referral. CONCLUSIONS Faecal calprotectin can be a highly sensitive way of detecting IBD, although there are inevitably trade-offs between sensitivity and specificity, with some false positives (IBS with positive calprotectin) if a low calprotectin cut-off is used. In most cases, a negative calprotectin rules out IBD, thereby sparing most people with IBS from having to have invasive investigations, such as colonoscopy. STUDY REGISTRATION PROSPERO CRD 42012003287. FUNDING The National Institute for Health Research Health Technology Assessment programme.

Glucagon-like peptide analogues for type 2 diabetes mellitus : systematic review and meta-analysis

BackgroundGlucagon-like peptide (GLP-1) analogues are a new class of drugs used in the treatment of type 2 diabetes. They are given by injection, and regulate glucose levels by stimulating glucose-dependent insulin secretion and biosynthesis, suppressing glucagon secretion, and delaying gastric emptying and promoting satiety. This systematic review aims to provide evidence on the clinical effectiveness of the GLP-1 agonists in patients not achieving satisfactory glycaemic control with one or more oral glucose lowering drugs.MethodsMEDLINE, EMBASE, the Cochrane Library and Web of Science were searched to find the relevant papers. We identified 28 randomised controlled trials comparing GLP-1 analogues with placebo, other glucose-lowering agents, or another GLP-1 analogue, in patients with type 2 diabetes with inadequate control on a single oral agent, or on dual therapy. Primary outcomes included HbA1c, weight change and adverse events.ResultsStudies were mostly of short duration, usually 26 weeks. All GLP-1 agonists reduced HbA1c by about 1% compared to placebo. Exenatide twice daily and insulin gave similar reductions in HbA1c, but exenatide 2 mg once weekly and liraglutide 1.8 mg daily reduced it by 0.20% and 0.30% respectively more than glargine. Liraglutide 1.2 mg daily reduced HbA1c by 0.34% more than sitagliptin 100 mg daily. Exenatide and liraglutide gave similar improvements in HbA1c to sulphonylureas. Exenatide 2 mg weekly and liraglutide 1.8 mg daily reduced HbA1c by more than exenatide 10 μg twice daily and sitagliptin 100 mg daily. Exenatide 2 mg weekly reduced HbA1c by 0.3% more than pioglitazone 45 mg daily.Exenatide and liraglutide resulted in greater weight loss (from 2.3 to 5.5 kg) than active comparators. This was not due simply to nausea. Hypoglycaemia was uncommon, except when combined with a sulphonylurea. The commonest adverse events with all GLP-1 agonists were initial nausea and vomiting. The GLP-1 agonists have some effect on beta-cell function, but this is not sustained after the drug is stopped.ConclusionsGLP-1 agonists are effective in improving glycaemic control and promoting weight loss.

Current treatments in diabetic macular oedema: systematic review and meta-analysis

Objectives The aim of this systematic review is to appraise the evidence for the use of anti-VEGF drugs and steroids in diabetic macular oedema (DMO) as assessed by change in best corrected visual acuity (BCVA), central macular thickness and adverse events Data source MEDLINE, EMBASE, Web of Science with Conference Proceedings and the Cochrane Library (inception to July 2012). Certain conference abstracts and drug regulatory web sites were also searched. Study eligibility criteria, participants and interventions Randomised controlled trials were used to assess clinical effectiveness and observational trials were used for safety. Trials which assessed triamcinolone, dexamethasone, fluocinolone, bevacizumab, ranibizumab, pegaptanib or aflibercept in patients with DMO were included. Study appraisal and synthesis methods Risk of bias was assessed using the Cochrane risk of bias tool. Study results are narratively described and, where appropriate, data were pooled using random effects meta-analysis. Results Anti-VEGF drugs are effective compared to both laser and placebo and seem to be more effective than steroids in improving BCVA. They have been shown to be safe in the short term but require frequent injections. Studies assessing steroids (triamcinolone, dexamethasone and fluocinolone) have reported mixed results when compared with laser or placebo. Steroids have been associated with increased incidence of cataracts and intraocular pressure rise but require fewer injections, especially when steroid implants are used. Limitations The quality of included studies varied considerably. Five of 14 meta-analyses had moderate or high statistical heterogeneity. Conclusions and implications of key findings The anti-VEGFs ranibizumab and bevacizumab have consistently shown good clinical effectiveness without major unwanted side effects. Steroid results have been mixed and are usually associated with cataract formation and intraocular pressure increase. Despite the current wider spectrum of treatments for DMO, only a small proportion of patients recover good vision (≥20/40), and thus the search for new therapies needs to continue.

Insulin sensitisers in the treatment of non-alcoholic fatty liver disease : a systematic review

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is closely linked with obesity and the prevalence of NAFLD is about 17% to 33% in the Western world. There is a strong association of NAFLD with insulin resistance and, hence, insulin sensitisers have been tried. This systematic review examined the clinical effectiveness of insulin sensitisers in patients with NAFLD, to help decide whether or not a trial or trials of the insulin sensitisers was necessary and also to explore whether or not non-invasive alternatives to liver biopsy were available that could be used in a large trial of the insulin sensitisers. OBJECTIVE To review the use of insulin sensitisers in the treatment of NAFLD. REVIEW METHODS A systematic review of the clinical effectiveness of metformin, rosiglitazone and pioglitazone was carried out, including reviews and randomised controlled trials (RCTs). Databases searched were MEDLINE, 1950 to June 2010; EMBASE, 1980 to June 2010; Science Citation Index Expanded, June 2010; Conference Proceedings Citation Index - Science June 2010; The Cochrane Library 2005-10. Abstracts were screened independently by two researchers. A narrative review of diagnostic methods was conducted. RESULTS Clinical effectiveness. We identified 15 RCTs (one available as abstract). Four papers explored efficacy of pioglitazone, one rosiglitazone, eight metformin; two compared metformin and rosiglitazone, although one used both metformin and rosiglitazone. The duration of most trials was between 6 and 12 months. Many trials had a small number of participants and the quality of the studies was mixed. Pioglitazone improved all parameters of liver histology. Metformin showed mixed results, with ultrasound changes in two studies showing some improvement in steatosis, whereas there were no changes in the other two. Metformin, however, showed no improvement in non-alcoholic steatohepatitis (NASH) stages. Metformin showed greater reduction in glycosylated haemoglobin (-0.23% to -1.2% vs -0.2% to -0.7%) and fasting plasma glucose (+0.05 to -3.19 mmol/l vs -0.17 to -1.11 mmol/l) compared with pioglitazone. Metformin led to weight reduction (-4.3 to -6.7 kg), whereas participants on pioglitazone gained weight (+2.5 to +4.7 kg). Alanine aminotransferase levels were reduced with both metformin and pioglitazone; however, the reduction in levels with pioglitazone was not different to that caused by vitamin E. Most studies suggested that metformin led to a significant reduction in insulin resistance. Diagnosis. Non-invasive methods of diagnosing NAFLD without liver biopsy, using combinations of clinical history, laboratory tests and ultrasound, have been explored, but so far liver biopsy is the only proven method of distinguishing simple steatosis from NASH. Transient elastography appears useful, but less so in obese individuals. Magnetic resonance spectroscopy shows promise, but is expensive and not readily available. LIMITATIONS Mixed quality of trials, with lack of detail as to how some trials were conducted. Many trials had small numbers of patients. CONCLUSIONS The main need for drug trials is at the NASH stage. However, at present, any trial in the more advanced forms of NAFLD would have to use liver biopsy. The highest priority for research may, therefore, be in the diagnosis of NAFLD, and the differentiation between steatosis and NASH. The newer agents, the glucagon-like peptide-1 analogues such as liraglutide, may be more worthy of a trial. FUNDING The National Institute for Health Research Health Technology Assessment programme.

Adding Pioglitazone to Insulin Containing Regimens in Type 2 Diabetes: Systematic Review and Meta-Analysis

Background Type 2 diabetes is treated in a stepwise manner, progressing from diet and physical activity to oral antidiabetic agents and insulin. The oral agent pioglitazone is licensed for use with insulin when metformin is contraindicated or not tolerated. This systematic review and meta-analysis investigates the extent to which adding pioglitazone to insulin-containing regimens produces benefits in terms of patient-relevant outcomes. Methodology/Principal Findings Medline, Embase, and the Cochrane Library were searched for randomised controlled trials comparing pioglitazone in combination with any insulin-containing regimen in comparison with the same insulin regimen alone in patients with type 2 diabetes. Outcomes investigated included HbA1c, hypoglycaemia, weight, and adverse events. Studies were selected, assessed and summarised according to standard systematic review methodology and in a meta-analysis. We included eight trials that examined the benefits of adding pioglitazone to an insulin regimen and studied a total of 3092 patients with type 2 diabetes. All studies included patients with previously inadequate glucose control. Trial duration was between 12 weeks and 34.5 months. The trials used pioglitazone doses of up to 45 mg/day. In our meta-analysis, the mean reduction in HbA1c was 0.58% (95% CI: −0.70, −0.46, p<0.00001). Hypoglycaemic episodes were slightly more frequent in the pioglitazone arms (relative risk 1.27; 95% CI: 0.99, 1.63, p = 0.06). Where reported, HDL-cholesterol tended to be increased with pioglitazone. Patients on pioglitazone tended to gain more weight than those who were not, with an average difference of almost 3 kg. Peripheral oedema was more frequent in the pioglitazone groups. None of the studies reported on fractures in women, and data on cardiovascular events were inconclusive, with most studies being too short or too small to assess these long-term outcomes. Conclusions/Significance When added to insulin regimens, pioglitazone confers a small advantage in terms of HbA1c in type 2 diabetes patients with previous inadequate glucose control, but at the cost of increased hypoglycaemia and weight gain. Other considerations include the risk of heart failure, fractures in women, a reduced insulin dose, and the net financial cost.

Cost-Effectiveness of Manual Therapy for the Management of Musculoskeletal Conditions: A Systematic Review and Narrative Synthesis of Evidence From Randomized Controlled Trials

OBJECTIVES The purpose of this study was to systematically review trial-based economic evaluations of manual therapy relative to other alternative interventions used for the management of musculoskeletal conditions. METHODS A comprehensive literature search was undertaken in major medical, health-related, science and health economic electronic databases. RESULTS Twenty-five publications were included (11 trial-based economic evaluations). The studies compared cost-effectiveness and/or cost-utility of manual therapy interventions to other treatment alternatives in reducing pain (spinal, shoulder, ankle). Manual therapy techniques (e.g., osteopathic spinal manipulation, physiotherapy manipulation and mobilization techniques, and chiropractic manipulation with or without other treatments) were more cost-effective than usual general practitioner (GP) care alone or with exercise, spinal stabilization, GP advice, advice to remain active, or brief pain management for improving low back and shoulder pain/disability. Chiropractic manipulation was found to be less costly and more effective than alternative treatment compared with either physiotherapy or GP care in improving neck pain. CONCLUSIONS Preliminary evidence from this review shows some economic advantage of manual therapy relative to other interventions used for the management of musculoskeletal conditions, indicating that some manual therapy techniques may be more cost-effective than usual GP care, spinal stabilization, GP advice, advice to remain active, or brief pain management for improving low back and shoulder pain/disability. However, at present, there is a paucity of evidence on the cost-effectiveness and/or cost-utility evaluations for manual therapy interventions. Further improvements in the methodological conduct and reporting quality of economic evaluations of manual therapy are warranted in order to facilitate adequate evidence-based decisions among policy makers, health care practitioners, and patients.

Treatments for macular oedema following central retinal vein occlusion:systematic review

Objectives To review systematically the randomised controlled trial (RCT) evidence for treatment of macular oedema due to central retinal vein occlusion (CRVO). Data sources MEDLINE, EMBASE, CDSR, DARE, HTA, NHSEED, CENTRAL and meeting abstracts (January 2005 to March 2013). Study eligibility criteria, participants and interventions RCTs with at least 12 months of follow-up assessing pharmacological treatments for CRVO were included with no language restrictions. Study appraisal and synthesis methods 2 authors screened titles and abstracts and conducted data extracted and Cochrane risk of bias assessment. Meta-analysis was not possible due to lack of comparable studies. Results 8 studies (35 articles, 1714 eyes) were included, assessing aflibercept (n=2), triamcinolone (n=2), bevacizumab (n=1), pegaptanib (n=1), dexamethasone (n=1) and ranibizumab (n=1). In general, bevacizumab, ranibizumab, aflibercept and triamcinolone resulted in clinically significant increases in the proportion of participants with an improvement in visual acuity of ≥15 letters, with 40–60% gaining ≥15 letters on active drugs, compared to 12–28% with sham. Results for pegaptanib and dexamethasone were mixed. Steroids were associated with cataract formation and increased intraocular pressure. No overall increase in adverse events was found with bevacizumab, ranibizumab, aflibercept or pegaptanib compared with control. Quality of life was poorly reported. All studies had a low or unclear risk of bias. Limitations All studies evaluated a relatively short primary follow-up (1 year or less). Most had an unmasked extension phase. There was no head-to-head evidence. The majority of participants included had non-ischaemic CRVO. Conclusions and implications of key findings Bevacizumab, ranibizumab, aflibercept and triamcinolone appear to be effective in treating macular oedema secondary to CRVO. Long-term data on effectiveness and safety are needed. Head-to-head trials and research to identify ‘responders’ is needed to help clinicians make the right choices for their patients. Research aimed to improve sight in people with ischaemic CRVO is required.