Frailty Screening is Associated with Hospitalization and Decline in Quality of Life and Functional Status in Older Patients with Inflammatory Bowel Disease

BACKGROUND AND AIMS

Our goals were to study frailty screening in association with hospitalization and decline in quality of life [QoL] and functional status in older patients with inflammatory bowel diseases [IBD].

METHODS

This was a prospective multicentre cohort study in IBD patients ≥65 years old using frailty screening [G8 Questionnaire]. Outcomes were all-cause, acute, and IBD-related hospitalization, any infection, any malignancy, QoL [EQ5D-3L], and functional decline (Instrumental Activities of Daily Living [IADL]) during 18 months of follow-up. Confounders were age, IBD type, biochemical disease activity [C-reactive protein ≥10 mg/L and/or faecal calprotectin ≥250 µg/g], and comorbidity [Charlson Comorbidity Index].

RESULTS

Of 405 patients, with a median age of 70 years, 196 [48%] were screened as being at risk for frailty. All-cause hospitalizations occurred 136 times in 96 patients [23.7%], and acute hospitalizations 103 times in 74 patients [18.3%]. Risk of frailty was not associated with all-cause (adjusted hazard ratio [aHR] 1.5, 95% confidence interval [CI] 0.9-2.4), but was associated with acute hospitalizations [aHR 2.2, 95% CI 1.3-3.8]. Infections occurred in 86 patients [21.2%] and these were not associated with frailty. A decline in QoL was experienced by 108 [30.6%] patients, and a decline in functional status by 46 patients [13.3%]. Frailty screening was associated with a decline in QoL (adjusted odds ratio [aOR] 2.1, 95% CI 1.3-3.6) and functional status [aOR 3.7, 95% CI 1.7-8.1].

CONCLUSIONS

Frailty screening is associated with worse health outcomes in older patients with IBD. Further studies are needed to assess the feasibility and effectiveness of its implementation in routine care.

Deficits in geriatric assessment are important in relation to fatigue in older patients with Inflammatory Bowel Disease

BACKGROUND

No previous study has investigated fatigue in older patients with Inflammatory Bowel Disease (IBD).

AIMS

To describe the prevalence of fatigue in older patients and compare it to the prevalence in younger patients with IBD, and to determine factors associated with fatigue.

METHODS

A prospective, multicenter cohort study, including older- (≥ 65 years) and younger patients with IBD (18-64 years). A geriatric assessment was performed in older patients to measure deficits in geriatric assessment (DiG). Fatigue was defined by one item from the short Inflammatory Bowel Disease Questionnaire. Active disease was defined as the presence of clinical or biochemical disease activity.

RESULTS

Fatigue prevalence in the 405 older patients varied between 45.4% (71/155) in active disease to 23.6% (60/250) in remission. Fatigue prevalence in 155 younger patients was 59.5% (47/79) and 57.4% (89/155), respectively. Female sex, clinical disease activity, use of immunomodulators and presence of DiG were associated with fatigue in older patients with IBD.

CONCLUSIONS

Fatigue prevalence is lower in older patients with IBD compared to younger patients with IBD, but increases when active disease is present. Clinicians should be aware that fatigue is a relevant symptom in older patients with IBD, as it is associated with DiG.

Deficits in Geriatric Assessment Associate With Disease Activity and Burden in Older Patients With Inflammatory Bowel Disease

BACKGROUND & AIMS

We aimed to perform geriatric assessment in older patients with inflammatory bowel disease (IBD) to evaluate which IBD characteristics associate with deficits in geriatric assessment and the impact of deficits on disease burden (health-related quality of life).

METHODS

A prospective multicenter cohort study including 405 consecutive outpatient patients with IBD aged ≥65 years. Somatic domain (comorbidity, polypharmacy, malnutrition), impairments in (instrumental) activities of daily living, physical capacity (handgrip strength, gait speed), and mental (depressive symptoms, cognitive impairment) and social domain (life-partner) were assessed. Deficits in geriatric assessment were defined as ≥2 abnormal domains; 2-3 moderate deficits and 4-5 severe deficits. Clinical (Harvey Bradshaw Index >4/partial Mayo Score >2) and biochemical (C-reactive protein ≥10 mg/L and/or fecal calprotectin ≥250 μg/g) disease activity and disease burden (short Inflammatory Bowel Disease Questionnaire) were assessed.

RESULTS

Somatic domain (51.6%) and activities of daily living (43.0%) were most frequently impaired. A total of 160 (39.5%) patients had moderate deficits in their geriatric assessment; 32 (7.9%) severe. Clinical and biochemical disease activity associated with deficits (clinical: adjusted odds ratio, 2.191; 95% confidence interval, 1.284-3.743; P = .004; biochemical: adjusted odds ratio, 3.358; 95% confidence interval, 1.936-5.825; P < .001). Deficits in geriatric assessment independently associate with lower health-related quality of life.

CONCLUSION

Deficits in geriatric assessment are highly prevalent in older patients with IBD. Patients with active disease are more prone to deficits, and deficits associate with lower health-related quality of life, indicating higher disease burden. Prospective data validating impact of frailty and geriatric assessment on outcomes are warranted to further improve treatment strategies.

Statin use is associated with a reduced incidence of colorectal cancer expressing SMAD4

BACKGROUND

Long-term use of statins is associated with a small reduced risk of colorectal cancer but their mechanism of action is not well understood. While they are generally believed to act on KRAS, we have previously proposed that they act via influencing the BMP pathway. The objective of this study was to look for associations between statin use and the risk of developing colorectal cancer of a particular molecular subtype.

METHODS

By linking two registries unique to the Netherlands, 69,272 statin users and 94,753 controls were identified and, if they developed colorectal cancer, their specimens traced. Colorectal cancers were molecularly subtyped according to the expression of SMAD4 and the mutation status of KRAS and BRAF.

RESULTS

Statin use was associated with a reduction in the risk of developing colorectal cancer regardless of molecular subtype (HR 0.77; 95% CI 0.66-0.89) and a larger reduction in the risk of developing SMAD4-positive colorectal cancer (OR 0.64; 95% CI 0.42-0.82). There was no relationship between statin use and the risk of developing colorectal cancer with a mutation in KRAS and/or BRAF.

CONCLUSIONS

Statin use is associated with a reduced risk of developing colorectal cancer with intact SMAD4 expression.

Statin Use After Diagnosis of Colon Cancer and Patient Survival

BACKGROUND & AIMS

Statin use has been associated with a reduced incidence of colorectal cancer and might also affect survival of patients diagnosed with colon cancer. Statins are believed to inhibit Ras signaling and may also activate the bone morphogenetic protein (BMP) signaling pathway in colorectal cancer cells. We investigated the effects of statins on overall survival of patients with a diagnosis of colon cancer, and whether their effects were associated with changes in KRAS or the BMP signaling pathways.

METHODS

Data were derived from the PHARMO database network (Netherlands) and linked to patients diagnosed with colon cancer from 2002 through 2007, listed in the Eindhoven Cancer Registry. We obtained information on causes of death from statistics Netherlands. We constructed a tissue microarray of 999 colon cancer specimens from patients who underwent surgical resection from 2002 through 2008. Survival was analyzed with statin user status after diagnosis as a time-dependent covariate. Multivariable Poisson regression survival models and Cox analyses were used to study the effect of statins on survival. Tumor tissues were analyzed by immunohistochemistry for levels of SMAD4, BMPR1A, BMPR1B, and BMPR2 proteins. Tumor tissues were considered to have intact BMP signaling if they contained SMAD4 plus BMPR1A, BMPR1B, or BMPR2. DNA was isolated from tumor tissues and analyzed by quantitative polymerase chain reaction to detect mutations in KRAS. The primary outcome measures were overall mortality and cancer-specific mortality.

RESULTS

In this cohort, 21.0% of the patients (210/999) were defined as statin users after diagnosis of colon cancer. Statin use after diagnosis was significantly associated with reduced risk of death from any cause (adjusted relative risk [RR], 0.67; 95% confidence interval [CI], 0.51-0.87; P = .003) and death from cancer (adjusted RR, 0.66; 95% CI, 0.49-0.89; P = .007). Statin use after diagnosis was associated with reduced risk of death from any cause or from cancer for patients whose tumors had intact BMP signaling (adjusted RR, 0.39; 95% CI, 0.22-0.68; P = .001), but not for patients whose tumors did not have BMP signaling (adjusted RR, 0.81; 95% CI, 0.55-1.21; P = .106; P < .0001 for the interaction). Statin use after diagnosis was not associated with reduced risk of death from any cause or from cancer for patients whose tumors did not contain KRAS mutations (adjusted RR, 0.81; 95% CI, 0.56-1.18; P = .273) or whose tumors did have KRAS mutations (adjusted RR, 0.59; 95% CI 0.35-1.03; P = .062; P = .90 for the interaction).

CONCLUSIONS

In an analysis of 999 patients with a diagnosis of colon cancer, we associated statin with reduced risk of death from any cause or from cancer. The benefit of statin use is greater for patients whose tumors have intact BMP signaling, independent of KRAS mutation status. Randomized controlled trials are required to confirm these results.

A Meta-Analysis of SMAD4 Immunohistochemistry as a Prognostic Marker in Colorectal Cancer

AIM: SMAD4 immunohistochemistry is considered a valuable prognostic marker in colorectal cancer, but individual studies have often been small and the results variable. A meta-analysis could potentially clarify these findings. METHODS: In September 2014, a Pubmed and Google Scholar search was conducted to find publications that reported the prognostic value of SMAD4 expression. A meta-analysis was performed to clarify the association between SMAD4 expression and survival outcomes. RESULTS: 137 studies were found, of which 13 were considered eligible. The studies consisted of a total of 3800 patients. Three different endpoints were taken into account, namely, overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS). In addition, the studies were divided into univariate and multivariate analyses. The pooled hazard ratios were given as follows: univariate CSS = 1.75 [95% confidence interval (CI): 0.93-3.32; z= 1.69; P= .09]; multivariate CSS = 2.17 (95% CI: 1.56-3.01; z= 4.65; P= .000); univariate DFS = 2.11 (95% CI: 1.36-3.28; z= 3.32; P= .001); multivariate DFS = 2.15 (95% CI: 1.56-3.01; z= 4.65; P= .000); univariate OS and DFS = 2.30 (95% CI: 1.41-3.73; z= 3.36; P= .001); univariate OS = 2.28 (95% CI: 1.30-4.00; z= 2.89; P= .004). CONCLUSION: The results of the presented meta-analyses indicate that SMAD4 expression status using immunohistochemistry is a prognostic marker for patient survival.

Loss of SMAD4 alters BMP signaling to promote colorectal cancer cell metastasis via activation of Rho and ROCK

BACKGROUND & AIMS

SMAD4 frequently is lost from colorectal cancers (CRCs), which is associated with the development of metastases and a poor prognosis. SMAD4 loss is believed to alter transforming growth factor β signaling to promote tumor progression. However, SMAD4 is also a central component of the bone morphogenetic protein (BMP) signaling pathway, implicated in CRC pathogenesis by human genetic studies. We investigated the effects of alterations in BMP signaling on the invasive and metastatic abilities of CRC cells and changes in members in this pathway in human tumor samples.

METHODS

We activated BMP signaling in SMAD4-positive and SMAD4-negative CRC cells (HCT116, HT-29, SW480, and LS174T); SMAD4 was stably expressed or knocked down using lentiviral vectors. We investigated the effects on markers of epithelial-mesenchymal transition and on cell migration, invasion, and formation of invadopodia. We performed kinase activity assays to characterize SMAD4-independent BMP signaling and used an inhibitor screen to identify pathways that regulate CRC cell migration. We investigated the effects of the ROCK inhibitor Y-27632 in immunocompromised (CD-1 Nu) mice with orthotopic metastatic tumors. Immunohistochemistry was used to detect BMPR1a, BMPR1b, BMPR2, and SMAD4 in human colorectal tumors; these were related to patient survival times.

RESULTS

Activation of BMP signaling in SMAD4-negative cells altered protein and messenger RNA levels of markers of epithelial-mesenchymal transition and increased cell migration, invasion, and formation of invadopodia. Knockdown of the BMP receptor in SMAD4-negative cells reduced their invasive activity in vitro. SMAD4-independent BMP signaling activated Rho signaling via ROCK and LIM domain kinase (LIMK). Pharmacologic inhibition of ROCK reduced metastasis of colorectal xenograft tumors in mice. Loss of SMAD4 from colorectal tumors has been associated with reduced survival time; we found that this association is dependent on the expression of BMP receptors but not transforming growth factor β receptors.

CONCLUSIONS

Loss of SMAD4 from colorectal cancer cells causes BMP signaling to switch from tumor suppressive to metastasis promoting. Concurrent loss of SMAD4 and normal expression of BMP receptors in colorectal tumors was associated with reduced survival times of patients. Reagents that interfere with SMAD4-independent BMP signaling, such as ROCK inhibitors, might be developed as therapeutics for CRC.

Reduced expression of bone morphogenetic protein receptor IA in pancreatic cancer is associated with a poor prognosis

Background:

The expression of SMAD4, the central component of the transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signalling pathways, is lost in 50% of pancreatic cancers and is associated with a poor survival. Although the TGF-β pathway has been extensively studied and characterised in pancreatic cancer, there is very limited data on BMP signalling, a well-known tumour-suppressor pathway. BMP signalling can be lost not only at the level of SMAD4 but also at the level of BMP receptors (BMPRs), as has been described in colorectal cancer.

Methods:

We performed immunohistochemical analysis of the expression levels of BMP signalling components in pancreatic cancer and correlated these with survival. We also manipulated the activity of BMP signalling in vitro.

Results:

Reduced expression of BMPRIA is associated with a significantly worse survival, primarily in a subset of SMAD4-positive cancers. In vitro inactivation of SMAD4-dependent BMP signalling increases proliferation and invasion of pancreatic cancer cells, whereas inactivation of BMP signalling in SMAD4-negative cells does not change the proliferation and invasion or leads to an opposite effect.

Conclusion:

Our data suggest that BMPRIA expression is a good prognostic marker and that the BMP pathway is a potential target for future therapeutic interventions in pancreatic cancer.

An assessment of the iPad as a testing platform for distance visual acuity in adults

OBJECTIVES

Visual acuity is a common measurement in general practice, and the advent of new technology such as tablet computers offers a change in the way in which these tests are delivered. The aim of this study was to assess whether measurements of distance visual acuity using LogMAR letter charts displayed on an iPad tablet computer were in agreement with standard clinical tests of visual acuity in adults with normal vision.

DESIGN

Blinded, diagnostic test study.

SETTING

Single centre (University) in Auckland, New Zealand.

PARTICIPANTS

University staff and students (n=85). Participants were required to have visual acuity better than 6/60 and wear habitual refractive correction during testing. Participants were excluded if there was any history of ocular pathology.

PRIMARY AND SECONDARY OUTCOME MEASURES

Visual acuity measured under a number of conditions.

RESULTS

The iPad tablet with its glossy screen was highly susceptible to glare resulting in acuity measurements that were significantly poorer (approximately 2 LogMAR lines) than those made using an ETDRS chart and a standard computerised testing system (n=56). However, fitting the iPad with an antiglare screen and positioning the device away from sources creating reflected (veiling) glare resulted in acuity measurements that were equivalent those made using gold standard charts (n=29).

CONCLUSIONS

Tablet computers are an attractive option for visual acuity measurement due to portability, the ability to randomise letters, automated scoring of acuity and the ability to select from a range of charts. However, these devices are only suitable for use in situations where sources of glare can be eliminated.

Cholesterol metabolism and colorectal cancers

Colorectal cancer (CRC) is primarily a lifestyle disease of the western world. As such it can be likened to cardiovascular disease and indeed it shares many of the same risk factors. It is therefore perhaps unsurprising that cholesterol metabolism and colorectal cancer are also intricately linked. Many of the initial studies suggesting a link between dietary cholesterol, blood cholesterol levels and cholesterol lowering drugs were performed more than a decade ago. The most recent insights in this field are the result of meta-analyses, advances in pharmacogenetics and the new field of molecular pathological epidemiology. This review summarises the current evidence linking cholesterol metabolism with colorectal cancer including the suggested underlying molecular causes and the implications for colorectal cancer prevention.

The potential of statins for individualized colorectal cancer chemoprevention

Colorectal cancer is a leading cause of death by cancer in the western world. Despite major progress, even new chemotherapeutic regimens have had relatively little impact on long term survival in the approximately 50% of patients with advanced disease at presentation meaning that prevention is the only realistic way to reduce the burden of this disease. Many countries have implemented population-based screening methods to prevent colorectal cancer by the physical removal of its precursor lesion the adenoma, or to detect cancer at an earlier stage when it is amenable to surgical cure. However these programs have only been shown to reduce colorectal cancer deaths by 30% in those screened and therefore new or complimentary approaches are needed. One such approach is chemoprevention. A number of compounds have shown potential in reducing the incidence of colorectal cancer. Most widely known are NSAIDs but recently inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, also known as statins, commonly prescribed medications that lower serum cholesterol, have been shown to reduce colorectal cancer incidence. A critical issue in chemoprevention is the weighing of benefits against risks. In chemoprevention this balance is likely to be unfavourable when used in a wide unselected population even for the safest of compounds. Therapy should therefore be tailored to the individual patient. The balance will be more favourable in high risk groups such as individuals especially susceptible to neoplasia because of environmental risk factors, patients with inflammatory bowel disease, those with a hereditary predisposition and patients with a previous history of colorectal cancer or polyps. Furthermore colorectal cancer is not one disease but a heterogeneous group of diseases with different underlying molecular mechanisms. It is likely that both prevention and therapy will need to be tailored to the molecular subtype of the cancer in question. This may explain why studies of colorectal cancer in statin users do not show consistent protective effects. Evidence in vitro has shown a dichotomous effect of statins with either a cancer inhibiting or cancer promoting effect depending on their molecular subtype. Further studies are needed to determine in which patient groups statins can be used to prevent colorectal cancer and whether in other patients groups they should be avoided.

Statins augment the chemosensitivity of colorectal cancer cells inducing epigenetic reprogramming and reducing colorectal cancer cell 'stemness' via the bone morphogenetic protein pathway

BACKGROUND

Promoter hypermethylation is an important and potentially reversible mechanism of tumour suppressor gene silencing in cancer. Compounds that demethylate tumour suppressor genes and induce differentiation of cancer cells, but do not have toxic side effects, would represent an exciting option in cancer therapy. Statins are cholesterol-lowering drugs with an excellent safety profile and associated with a reduced incidence of various cancers including colorectal cancer (CRC). The authors have previously shown that statins act by activating tumour suppressive bone morphogenetic protein (BMP) signalling in CRC, increasing expression of BMP2. BMP2 is silenced by hypermethylation in gastric cancer.

AIM

To investigate whether BMP2 is methylated in CRC, whether statins can reverse this, and what implications this has for the use of statins in CRC.

METHODS

Methylation-specific PCR, bisulphite sequencing, immunoblotting, reverse transcription PCR, quantitative PCR, fluorescence-activated cell sorting analysis, an in vitro DNA methyltransferase (DNMT) assay, and cell viability studies were performed on CRC cells. The effect of statins was confirmed in a xenograft mouse model. Results BMP2 is silenced by promoter hypermethylation in cell lines with the hypermethylator phenotype and in primary tumours. Treatment with lovastatin downregulates DNMT activity, leading to BMP2 promoter demethylation and to upregulation of expression of BMP2 as well as other genes methylated in CRC. Statins alter gene expression, indicating a shift from a stem-like state to a more differentiated state, thereby sensitising cells to the effects of 5-fluorouracil. In a xenograft mouse model, simvastatin treatment induces BMP2 expression, leading to differentiation and reduced proliferation of CRC cells.

CONCLUSIONS

Statins act as DNMT inhibitors, demethylating the BMP2 promoter, activating BMP signalling, inducing differentiation of CRC cells, and reducing 'stemness'. This study indicates that statins may be able to be used as differentiating agents in combined or adjuvant therapy in CRC with the CpG island methylator phenotype.

Intestinal tumorigenesis is not affected by progesterone signaling in rodent models

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the Apc^Min/+ mouse, a model for spontaneous intestinal polyposis. PRKO-Apc^Min/+mice exhibited no change in polyp number, size or localization compared to Apc^Min/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

The role of EZH2 and DNA methylation in the silencing of the tumour suppressor RUNX3 in colorectal cancer

In gastric cancer, a new epigenetic mechanism of tumour suppressor loss has been suggested where the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is responsible for loss of expression of RUNX3. This is consistent with EZH2 upregulation in multiple cancer types being associated with poor prognosis. We investigated whether EZH2 influences the expression of RUNX3 in colorectal cancer (CRC) and whether this is independent of methylation. We determined protein and messenger RNA (mRNA) levels of EZH2 and RUNX3 and assessed RUNX3 methylation with methylation-specific polymerase chain reaction using 72 human CRCs and 8 CRC cell lines. We assessed the effect of efficient RNA interference-mediated knockdown of EZH2 on RUNX3 levels, cell viability and H3K27 trimethylation of the RUNX3 promoter using chromatin immunoprecipitation. Despite higher levels of EZH2 and lower levels of RUNX3 in CRC specimens in general, no inverse correlation between EZH2 and RUNX3 in paired samples was found arguing against a major role for histone methylation in silencing RUNX3 in CRC. Conversely, downregulation of RUNX3 mRNA in the same tumours was associated with RUNX3 DNA methylation (P < 0.05). In cell lines, knockdown of EZH2 removed the repressive chromatin marks from RUNX3 but did not result in RUNX3 re-expression. However, it prevented the re-silencing of RUNX3 after the removal of demethylating agents. In conclusion, DNA methylation is primarily responsible for the transcriptional silencing of RUNX3 in CRC, but EZH2 and histone methylation are necessary for its methylation-dependent re-silencing after the removal of demethylating agents. These results would predict that inhibitors of EZH2 and histone methylation would enhance the effects of demethylating agents in cancer therapy.

Key elements of the BMP/SMAD pathway co-localize with CDX2 in intestinal metaplasia and regulate CDX2 expression in human gastric cell lines

Helicobacter pylori infection induces intestinal metaplasia of the stomach, a preneoplastic lesion associated with an increased risk for gastric cancer development. Intestinal metaplasia is induced by the intestine-specific transcription factor CDX2 but the mechanisms responsible for this ectopic expression have never been described. We hypothesized that the BMP/SMAD pathway has a role in CDX2 regulation, in this context, for the following reasons: (1) the BMP pathway is crucial for normal intestinal differentiation and (2) there is an influx of BMP2 and BMP4-producing cells to the stomach upon Helicobacter pylori infection. We evaluated the expression of key elements of the BMP pathway in human stomach specimens with IM. Growth factor treatments, with BMP2 and BMP4, were performed in cultured cells and a knock-down experiment of SMAD4 was done using RNAi. We showed overexpression in IM of BMP2/4, BMPR1A, and SMAD4 in 56% of IM foci, and pSMAD1/5/8 in 100% of IM foci as compared to adjacent mucosa. In vitro, treatment of AGS cells with BMP2 and BMP4 increased endogenous CDX2 expression as well as the intestinal differentiation markers MUC2 and LI-cadherin. On the other hand, SMAD4 knock-down led to decreased endogenous CDX2, MUC2, and LI-cadherin in AGS. Treatment of the SMAD4 knock-down cells had no influence on CDX2 expression as opposed to wild-type cells. A 9.3 kb CDX2 promoter could be transactivated by SMAD4 and SMAD1 in a cell-dependent manner. In conclusion, we identified for the first time that the BMP pathway is active in intestinal metaplasia and that BMP2 and BMP4 regulate CDX2 expression and promote intestinal differentiation through the canonical signal transducers.

Do too many shots due lead to missed vaccination opportunities? Does it matter?

BACKGROUND

Missed childhood vaccination opportunities have been generally described, yet not since the immunization schedule's recent rapid expansion. Little is known about the relationship between the number of vaccine doses due and whether all scheduled doses are administered, and the effect of dose deferral on immunization coverage.

METHODS

32 private pediatrics centers reviewed medical records covering the first 2 years of life for 858 patients. For each visit during ages 2-8 months, we determined the numbers of vaccine doses due versus administered. Logistic regression was used to assess the effect of dose deferral on immunization coverage at ages 1 and 2 years.

RESULTS

Of 2224 visits during ages 2-8 months at which > or =1 dose was administered, > or =1 due dose was deferred at 26%, 34%, and 48% of the visits at which < or =3, 4, and 5 doses were due, respectively. Absence of a deferred dose visit predicted increased coverage at age 1 (adjusted odds ratio: 2.4, 95% confidence interval: 1.8-3.2) and 2 years (2.1, 1.4-3.0).

CONCLUSIONS

Administering some but not all vaccine doses at visits during ages 2-8 months impairs immunization coverage through age 2 years.

Clinician satisfaction with vaccination visits and the role of multiple injections, results from the COVISE Study (Combination Vaccines Impact on Satisfaction and Epidemiology)

Because little is known about clinician satisfaction with infant vaccination visits, we measured satistaction and the effects of the number of injections on satisfaction. Clinicians from 35 pediatric centers self-administered a questionnaire using visual analog scales augmented by a Likert scale. All 95 pediatricians and 137 nonphysician vaccinators responded. In both populations, increased injections predicted decreased overall satisfaction, and decreased satisfaction with obtaining consent, time to prepare/administer, getting upset during administration, and time to update records (each p<0.01). Satisfaction decreased markedly, on each measure, at 4-injection visits, 5-injection visits, or both.

Comparative cost effectiveness of varicella, hepatitis A, and pneumococcal conjugate vaccines

BACKGROUND

Several state and local U.S. governments are considering making varicella, hepatitis A, and/or pneumococcal conjugate vaccination conditions of day care or school entry. These requirements will likely be issued sequentially, because simultaneous mandates exacerbate budget constraints and complicate communication with parents and providers. Cost-effectiveness assessments should aid the establishment of vaccination priorities, but comparing results of published studies is confounded by their dissimilar methods.

METHODS

We reviewed U.S. cost-effectiveness studies of childhood varicella, hepatitis A, and pneumococcal conjugate vaccines and identified four providing data required to standardize methods. Vaccination, disease treatment, and work-loss costs were estimated from original study results and current prices. Estimated life-years saved were derived from original study results, epidemiological evidence, and alternative procedures for discounting to present values.

RESULTS

Hepatitis A vaccine would have the lowest health system costs per life-year saved. Varicella vaccine would provide the greatest reduction in societal costs, mainly through reduced parent work loss. Pneumococcal conjugate vaccine would cost twice the amount of varicella and hepatitis A vaccines combined and be less cost effective than the other vaccines.

CONCLUSIONS

Hepatitis A and varicella vaccines, but not pneumococcal conjugate vaccine, meet or exceed conventional standards of cost effectiveness.

Transmission of hepatitis A through household contact

In the USA, cost effectiveness assessments support childhood hepatitis A vaccination in geographical areas with elevated disease rates, but not nationally. However, these studies do not address the reduction in disease transmission which may result from routine childhood vaccination. Using decision analysis, we estimated the number and age distribution of secondary hepatitis A cases occurring within households with an index case. Based on the age of the index case, we determined household size and age composition, the proportion of household members susceptible to hepatitis A, the probability of disease transmission, and the likelihood secondarily infected household members would exhibit symptoms. Our model indicates that for every 100 index cases age 6-11 years, 47.2 secondary infections would occur within households, with 23.1 causing overt disease. Lower transmission rates for older index cases reflect smaller household sizes and a higher proportion of household contacts with hepatitis A immunity. When disease transmission rates are applied to a model simulating lifetime risks of hepatitis A, universal vaccination of an annual USA birth cohort is estimated to prevent 24 100 cases of overt disease among household contacts in addition to 71 000 cases among vaccinees. Sensitivity analysis provides a wide range of estimates, but even conservative assumptions suggest routine vaccination would yield an important reduction in secondary cases. Evaluations of hepatitis A prevention should consider the ability of immunization to protect household and other personal contacts.

Economic value to parents of reducing the pain and emotional distress of childhood vaccine injections

BACKGROUND

One reason that recommended childhood immunizations due at child health visits are deferred is to avoid the pain and emotional distress associated with the increasing number of injections required. This deferral leads to additional visits and costs and reduced immunoprotection against vaccine-preventable illnesses. To assess the economic value of combination vaccines that address this problem, we surveyed parents to determine the amount they would be willing to pay to avoid the pain and emotional distress experienced by their infants from injections.

METHODS

A self-administered questionnaire was completed within 24 h of the vaccinations by 294 parents of children ages 11/2 to 7 months receiving vaccine injections at 26 outpatient child health centers. The willingness-to-pay (WTP) method was used to estimate the intangible cost of the pain and emotional distress of the 1 to 4 injections their child had received. Parents were asked how much of their own money they would have paid to avoid these injections, without any compromise in the safety and efficacy of the vaccinations.

RESULTS

Wide variations in WTP amounts were observed, ranging from median values of $10 to $25 and average values of $57.06 to $79.28 to avoid the pain and emotional distress associated with eliminating all injections at visits in which one to four injections were administered. Parents placed greater value on reductions that avoided all injections than on reductions that avoided only some injections. Overall the median cost per injection avoided was $8.14, and the mean was $30.28.

CONCLUSIONS

Parents have strong preferences for limiting vaccine injections. The economic cost of the pain and distress associated with such injections, reflected in the amounts they report they would be willing to pay to avoid them, represents a substantial component of the cost of disease control through immunization.

Comparative safety of filgrastim versus sargramostim in patients receiving myelosuppressive chemotherapy

STUDY OBJECTIVE

To compare rates of adverse events with filgrastim versus sargramostim when given prophylactically to patients receiving myelosuppressive chemotherapy.

DESIGN

Retrospective review with center crossover.

SETTING

Ten United States outpatient chemotherapy centers.

PATIENTS

Four hundred ninety patients treated for lung, breast, lymphatic system, or ovarian tumors.

INTERVENTION

Prophylactic use of filgrastim or sargramostim, with dosages at investigator discretion.

MEASUREMENTS AND MAIN RESULTS

The frequency and severity of adverse events and the frequency of switching to the alternative CSF were assessed. There was no difference in infectious fever. Fever unexplained by infection was more common with sargramostim (7% vs 1%, p<0.001), as were fatigue, diarrhea, injection site reactions, other dermatologic disorders, and edema (all p<0.05). Skeletal pain was more frequent with filgrastim (p=0.06). Patients treated with sargramostim switched to the alternative agent more often (p<0.001).

CONCLUSION

Adverse events were less frequent with filgrastim than with sargramostim, suggesting that quality of life and treatment costs also may differ.

The cost-effectiveness of adolescent hepatitis A vaccination in states with the highest disease rates

BACKGROUND

The Advisory Committee on Immunization Practices has recommended routine childhood hepatitis A vaccination in states and communities where the incidence of disease exceeds the national average, but most adolescents are currently unprotected from infection.

OBJECTIVE

To estimate clinical and economic consequences of vaccinating adolescents against hepatitis A in the 10 states with the highest disease rates.

DESIGN

Decision analysis was used to assess cost-effectiveness from societal and health system perspectives. Parameter estimates were obtained from national surveillance data, a study of hepatitis A cases, and an expert panel.

MAIN OUTCOME MEASURES

Reduction in disease incidence; costs of vaccination, treatment, and work loss; years of life saved (YOLS); and costs per YOLS.

RESULTS

In states with the highest disease rates, vaccination of adolescents against hepatitis A would reduce the lifetime risk of symptomatic infection from 3.3% to 0.7% and prevent loss of 2117 years of life. Vaccination of a single birth cohort would cost $30.9 million, yet treatment and work loss costs would decline $14.2 million and $23.8 million, respectively. Hepatitis A vaccination would cost the health system $7902 per YOLS or $13,722 per discounted YOLS. Results are most sensitive to variation in the discount rate and assumptions regarding long-term vaccine protective efficacy.

CONCLUSIONS

Hepatitis A vaccination of adolescents in states with high disease rates would reduce costs to society. Although health system costs would increase, cost-effectiveness is comparable to other recommended vaccines and superior to many commonly used medical interventions. Arch Pediatr Adolesc Med. 2000;154:763-770

Cost effectiveness of vaccinating food service workers against hepatitis A infection

Foodborne transmission is an important means of hepatitis A infection that may be reduced through vaccination of food service workers (FSWs). Several states are considering actions to encourage or mandate FSW vaccination, but the cost effectiveness of such policies has not been assessed. We estimated the clinical and economic consequences of vaccinating FSWs from the 10 states with the highest reported rates of hepatitis A. A decision analytic model was used to predict the effects of vaccinating FSWs at age 20 years. It was assumed all FSWs would receive one dose of inactivated hepatitis A vaccine, and 50% would receive the second recommended dose. Parameter estimates were obtained from published reports and Centers for Disease Control and Prevention databases. The primary endpoint was cost per year of life saved (YOLS). Secondary endpoints were symptomatic infections, days of illness, deaths, and costs of hepatitis A treatment, public health intervention, and work loss. Each endpoint was considered separately for FSWs and patrons. We estimate vaccination of 100,000 FSWs would cost $8.1 million but reduce the costs of hepatitis A treatment, public health intervention, and work loss by $3.0 million, $2.3 million, and $3.1 million, respectively. Vaccination would prevent approximately 2,500 symptomatic infections, 93,000 days of illness, and 8 deaths. A vaccination policy would reduce societal costs while costing the health system $13,969 per YOLS, a ratio that exceeds generally accepted standards of cost effectiveness.

The cost of hepatitis A infections in American adolescents and adults in 1997

The incidence of hepatitis A has declined in the United States for several decades, leading to an increased number of susceptible adolescents and adults. Because clinical severity increases with age, hepatitis A infections in older individuals cause greater morbidity, mortality, and treatment costs. Because the economic burden of hepatitis A has not been well described, we estimated its costs, from the societal perspective, for patients infected at distinct ages. A case-series study described treatment patterns, work loss, and symptom duration. Disease outcomes were estimated by an expert panel. Economic losses were calculated by applying normative data reflecting treatment charges, employee compensation, and the value of housekeeping services. In the case-series study, mean treatment charges were $740 for nonhospitalized patients versus $6,914 for hospitalized patients (P <.001). Symptom duration (67.8 vs. 34.4 days, P <.001) and work loss (33.2 vs. 15.5 days, P <.01) were also greater for those hospitalized. Nationally, we estimate 63,363 symptomatic hepatitis A infections occurred among adolescents and adults during 1997, resulting in 8,403 hospital admissions and 255 deaths. Nearly 2.5 million days of symptomatic illness and 829,000 work-loss days resulted, and 7,466 years of life were lost. Under base-case assumptions, annual hepatitis A costs were estimated at $488.8 million. In sensitivity analyses, this estimate varied from $332.4 to $579.9 million. These costs may be reduced by regionally targeted vaccination of children, as recommended by the Advisory Committee on Immunization Practices, although the cost effectiveness of this policy has not yet been established.

Evaluation of office-based intervention to improve prevention counseling for patients at risk for sexually acquired hepatitis B virus infection. Hepatitis B-WARE Study Group

The aim of this study was to determine the effectiveness of tools to identify and counsel patients at risk for sexually transmitted hepatitis B virus infection. Physicians were randomly assigned to either an intervention group or a control group. The intervention group was provided with materials intended to encourage patients to return for counseling and to guide counseling concerning prevention of hepatitis B virus infection. Baseline data on 457 patients at risk for hepatitis B virus infection showed that 7% had received prevention counseling and 2% had begun hepatitis B vaccination. Counseling was least likely to occur in obstetric-gynecologic practices, among uninsured patients, and among patients whose only risk factor was a diagnosis of a sexually transmitted disease. After a 6-month intervention period 26% of the intervention group patients and 7% of the control group patients had been counseled (P <.01). Vaccination was more likely among intervention group patients (8% vs <1%; P <.001). The use of tools to identify and counsel patients at risk for sexually transmitted hepatitis B virus infection resulted in increased office-based prevention activities.

Influence of age on the multifocal electroretinography

The influence of age on the amplitude density (nV/sq deg) of the multifocal electroretinogram (ERG) was studied in 90 healthy subjects aged 18-52 years. Subjects were divided into three separate age groups; (i) 18-22 years (ii) 33-37 years and (iii) 48-52 years. Amplitude density of first order kernel of the multifocal ERG was measured for the three different age groups. When the whole response of the retina is considered, analysis of variance showed no significant differences in amplitude density between the three age groups. (ANOVA, df. 2, 87 F = 2.29, p = 0.11. However if the responses were segregated into a central area and concentric rings around the central area, analysis of variance showed that there were significant differences in responses between rings at different eccentricities and between different age groups (Anova F = 76.19, df. 17, 522, p = 0.00001). Post hoc analysis showed that the responses from the centre and the second ring around the centre of fixation for 48-52 year olds were significantly lower than those responses from the 33-37 year old and the 18-22 year old age groups. The decline in the multifocal ERG in the central retina of the 48-52 year olds could be associated with the decline of the number of photoreceptors as the eye ages. Student t test revealed no significant differences in amplitude density between males and females.

Study of luminance effects on pinhole test results for visually impaired patients

PURPOSE

The visual acuity of visually impaired patients has been reported to improve after a refraction, despite pinhole test results that show a decline or no change in acuity. Our aim was to investigate whether the pinhole-induced reduction in retinal illuminance accounted for these unreliable predictions of best-corrected acuity.

METHODS

Participants were 64 adult patients referred for low-vision rehabilitation. Neutral density filters reproduced the pinhole-induced luminance loss, allowing pinhole test and postrefraction acuities to be measured at essentially equivalent levels of retinal illuminance. The following data were collected in random order from each subject's better eye: (1) habitual visual acuity, (2) habitual visual acuity with filter, (3) habitual visual acuity with pinhole, (4) best-corrected/postrefraction visual acuity, (5) postrefraction visual acuity with filter.

RESULTS

On average, the pinhole test under-estimated postrefraction visual acuity by six letters (95% confidence limits = +/- 20). The pinhole test underestimated postrefraction visual acuity with the filter by two letters (95% confidence limits = +/- 16). Among subjects whose acuity improved with the pinhole test (N = 24), 83% experienced better postrefraction visual acuity. Among subjects whose acuity declined or remained unchanged with the pinhole test (N = 40), 50% achieved better postrefraction visual acuity.

CONCLUSIONS

The pinhole-induced luminance loss contributed to inadequate predictions of postrefraction visual acuity. Pinhole test results were enormously variable, underestimating and overestimating postrefraction visual acuity. The pinhole test was less reliable when improvements in postrefraction visual acuity were small. Visually impaired patients deserve periodic refractions, and the pinhole test result should not be used as a dichotomizer for clinical decisions regarding the need for a refraction.

The repeatability and variability of the multifocal electroretinogram for four different electrodes

Multifocal electroretinograms were recorded from twelve subjects on three separate days using the Visual Evoked Response Imaging System (VERIS). The subjects were 18-40 years-of-age. Each recording session was separated by an interval of between one and 16 weeks. Four electrode types were compared: the JET contact lens electrode, the gold foil electrode, the DTL thread electrode and the carbon fibre (c-glide) electrode. The b-wave amplitude density (nV/sq.deg) recorded with each electrode was measured. The mean amplitude density recorded at each session for each subject and each electrode was calculated and compared. There were no significant differences in amplitude density for the ERGs recorded with each type of electrode over the three days. The coefficient of variation for each electrode and each subject was then calculated using the results for the three days. The coefficients of variation for each electrode showed significant differences (One-way ANOVA: F = 4.51, d.f. = 3.44, P < 0.008). The c-glide electrode results had the highest variability and post hoc tests showed that its coefficient of variation was significantly different from those of the JET and gold foil electrodes but not from that of the DTL thread electrode.

The effects of clonazepam on quality of life and work productivity in panic disorder

Although panic disorder has been associated with impaired quality of life (QOL) and financial dependence, no prior study has examined whether a clinical intervention will improve these outcomes. This study examines the effects of clinically titrated doses of clonazepam versus placebo on QOL and work productivity (WP) in patients with panic disorder. QOL and WP were measured in conjunction with a randomized, double-blind, placebo-controlled trial. The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and Work Productivity and Impairment questionnaire were used to assess QOL and WP, respectively. Baseline assessments were obtained before randomizing patients to receive clinically titrated doses of clonazepam or placebo. Follow-up assessments were obtained after 6 weeks of therapy with the test drug or at premature termination from the study. Improvement on the SF-36 Mental Health Component Summary scale was more than twice as great with clonazepam than with placebo (P = 0.03). Clonazepam patients improved (P < 0.05) on all five measures of mental health-related QOL, and both measures of physical health-related QOL, and both measures of WP. Placebo patients improved on three of five measures of mental health-related QOL, but on no other measures. Patients with marked improvements on clinical measures of panic disorder severity, especially avoidance and fear of the main phobia, showed the greatest gains on the SF-36 Mental Health Component Summary scale. Clinically titrated doses of clonazepam significantly improved mental health-related QOL and WP in panic disorder patients. Lesser improvements were obtained with placebo.

The quality of life and employment in panic disorder

Our purpose was to measure quality of life (QOL) and work productivity (WP) in persons with panic disorder. Eighty-four panic disorder patients with limited psychiatric comorbidity for ten U.S. outpatient mental health centers were evaluated in a cross-sectional design. Patients self-administered the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and Work Productivity and Impairment (WPAI) questionnaire. The independent effects of psychiatric comorbidity were addressed through entry criteria, stratification, and regression analyses. QOL scores are significantly below age and sex-adjusted population norms on all SF-36 measures (p < .01). We note far greater impairment on measures of mental and emotional versus physical well-being. The unemployment rate among these patients is 25%, and only 57% are employed full-time. Those who are employed rated their WP as low. This sample of outpatients suffer marked QOL and employment impairment, which is only partially explained by the presence of psychiatric comorbidity.

A cost-effectiveness analysis of OKT3 induction therapy in cadaveric kidney transplantation

We evaluated the cost-effectiveness of a standard immunosuppressive regimen versus an OKT3 induction regimen in cadaveric kidney transplant recipients. Cost estimates were based on results from a five-center randomized trial comparing the safety and efficacy of OKT3 induction with a conventional triple-drug regimen and financial data from the National Cooperative Transplantation Study, the Medicare Provider and Analysis Review database, and other sources. Patients received OKT3 (5 mg/day) by intravenous (IV) bolus injection for 10 to 14 consecutive days in conjunction with azathioprine, prednisone, and the delayed addition of cyclosporine (CsA) on day 11 (n = 105) or a conventional immunosuppressive regimen consisting of CsA, azathioprine, and prednisone (n = 102). The following measures were used to evaluate the two regimens: costs incurred between transplantation and graft failure; the effectiveness of the two regimens as defined by length of graft survival; and cost-effectiveness ratios through 5 years of observed follow-up and modeled through the expected duration of graft survival. Results showed that OKT3 induction uniformly adds $8,219 to the cost of the transplant hospitalization. However, most of this cost is offset by a reduction in the cost of treating rejection episodes in the OKT3 group (P = 0.002). A trend toward improved graft survival was detected in the OKT3 group (P = 0.158). Through 5 years of observed follow-up, costs per year of graft survival are $30,474 with OKT3 versus $32,687 with the conventional regimen. Modeled through the expected duration of graft survival, OKT3 induction costs $8,335 for each additional year of graft survival. Results are fairly insensitive to wide variations in baseline assumptions. We conclude that OKT3 induction improves the cost-effectiveness of kidney transplantation.

Subjective and objective assessment of soft bifocal contact lens performance

Subjective and objective techniques were used to assess the on-eye performance of soft bifocal contact lenses. In the subjective technique a young observer whose accommodation had been paralyzed with a cycloplegic agent was fitted with the contact lens type under investigation and aligned with a Maxwellian view Badal optometer using a bite-bar. Visual acuity was measured as a function of both target vergence (0.00 to -4.00 D) and pupil size (1 to 5 mm). Aspheric, concentric, and diffractive soft bifocal contact lens designs were investigated. Diffractive and concentric bifocal designs with +2.00 D near additions showed "twin peaks" of visual acuity with one peak at 0.00 D target vergence (equivalent to distance viewing) and the second at -2.00 D target vergence (equivalent to a target at 50 cm). Some aspheric designs produced a relatively constant visual acuity across this vergence range, whereas others gave poor acuity at near. Visual acuity with the Echelon diffractive lens was relatively unaffected by pupil size, confirming theoretical predictions. Visual acuity with concentric designs was also relatively free of pupil size effects. In the objective technique, the variation in surface power across the lens was assessed using video-keratography. This technique provided an elegant means of visualizing the power profile of the lens. The location of the zones of increased power and the magnitude of power variations allowed an accurate prediction of the visual performance measured subjectively. Temporal displacement of lenses may explain the occasions where visual performance did not vary with pupil size.

Economic impact of hospitalizations for lower abdominal adhesiolysis in the United States in 1988

Much has been written about adhesion formation and prevention. Little is known about the number and cost of hospitalizations during which adhesiolysis is performed. This report describes the number of hospitalizations and days of care attributable to adhesiolysis in the United States and estimates the costs associated with these stays. The cost per hospital day and associated surgeons' fees are based on prevailing nationwide charges. During 1988, there were 281,982 hospitalizations during which adhesiolysis was performed, accounting for 948,727 days of inpatient care. These hospitalizations were responsible for an estimated $1,179.9 million in expenditures, of which $925.0 million was associated with hospital costs and $254.9 million with surgeons' fees. This estimate does not include outpatient costs and indirect costs. The results of this study demonstrate substantial costs associated with hospitalizations for adhesiolysis. Further understanding and prevention of adhesions may help to reduce unnecessary morbidity and mortality rates.

Pseudocyst of the auricle

BACKGROUND

Pseudocyst of the auricle is a benign swelling of the ear characterized by collection of fluid within an unlined intracartilaginous cavity. The etiology and pathogenesis of this disorder remain unknown. Various forms of management have been described in several case reports and small series.

OBJECTIVE

Description of a surgical procedure for successful management of pseudocyst of the auricle.

METHODS

Case report of a patient who declined nonsurgical treatment options following failed management with aspiration.

RESULTS

The described procedure resulted in cure of the pseudocyst with good cosmetic outcome.

CONCLUSION

Pseudocyst of the auricle can be successfully managed by surgical excision of the anterior wall of the cyst.

Artificial pupils and Maxwellian view

When control of the pupil size is required, the simplest method is to use a physical artificial pupil or aperture that is placed in the spectacle plane. In some clinical applications (e.g., the potential acuity meter) an optical artificial pupil is imaged in the plane of the natural pupil by a Maxwellian view optical system. We compared visual performance with physical and Maxwellian artificial pupils by measuring the effects of the pupil diameter (0.5-5 mm in range) and defocus (5-D myopia to 4-D hyperopia) on minimum angles of resolution (MAR's) and on angular blur disk diameters. For pupil diameters down to ~ 2.0 mm there were no meaningful differences between the visual resolution that is obtained with the physical and the Maxwellian pupils. At the smallest diameter (0.5 mm) the physical artificial pupils caused the MAR to increase because of the diffraction limitation on resolution, and defocus no longer affected MAR. With the small Maxwellian pupils vision did not become diffraction-limited so that maximum resolution could still be obtained. MAR was still affected by defocus. The angular blur disk diameters measured with the smaller Maxwellian pupils were slightly but significantly larger than those found with physical artificial pupils. For physical artificial pupils, field-of-view restrictions may result from vignetting with the eye pupil. Thus small physical artificial pupils can act as pinholes causing resolution to become impaired but insensitive to defocus. Also vignetting by the eye pupil can restrict the field of view. Small optical artificial pupils from Maxwellian viewing do not impair resolution, and the resolution may remain sensitive to defocus. The eye pupil does not cause any field restriction, although, if small, it may filter higher spatial frequencies out of the retinal image.

Radiation dose in temporomandibular joint zonography

Temporomandibular joint morphology and function can be evaluated by panoramic zonography. Thermoluminescent dosimetry was applied to evaluate the radiation dose to predetermined sites on a phantom eye, thyroid, pituitary, and parotid, and the dose distribution on the skin of the head and neck when the TMJ program of the Zonarc panoramic x-ray unit was used. Findings are discussed with reference to similar radiographic techniques.

Effect of defocus on blur thresholds and on thresholds of perceived change in blur: comparison of source and observer methods

The defocus levels required for normal observers to notice the first perceptible blur of a clear test target (blur threshold) and the least perceptible change in the degree of blurriness of an already blurry target (threshold of perceived change in blur) were measured using both the source and observer methods. In the source method observers viewed defocused stimuli presented on a projection screen, whereas in the observer method focused stimuli were presented to observers who were defocused using lenses placed in the spectacle plane. Blur thresholds were found to be dependent on target size and when the Landolt ring targets were near threshold acuity size blur thresholds were as small as 0.10 D. For larger target sizes (0.6 log min arc or more above threshold acuity size) the blur thresholds remained relatively unchanged and were about 0.18 D. Thresholds of perceived change in blur were found to be independent of the initial defocus level. Measurements of the threshold of perceived change in blur were found to be 0.05 to 0.07 D, which is much smaller than the blur threshold values. Comparison of results from the two methods of producing defocus indicate that the source and observer methods can be used interchangeably. However, for the same angular blur disc diameter, the blur thresholds found with the source method were significantly lower than those found with the observer method.

Effect of defocus on visual acuity as measured by source and observer methods

The relation between refractive error and visual acuity has been measured by two very different methods. In one called "source methods," emmetropes or corrected ametropes view defocused stimuli presented on projection screens or photographs. In the type called "observer methods," focused stimuli are presented to the observers who are either uncorrected ametropes or emmetropes defocused by lenses placed (usually), in the spectacle plane. The study reported in this paper demonstrates for the first time that these two methods of defocusing retinal images and their effects on visual acuity can be correlated. Results show that the source method of producing defocus could be used interchangeably with the observer method in investigating the rates of change of visual acuity with defocus for young normal observers. The angular diameter of the defocused image of a point, the blur disc diameter in object space, allows the two methods to be compared. Although the results show that the two methods are highly correlated, they show that the source method gives a statistically but not clinically significant lower acuity. The results of both methods are used to derive an equation linking refractive error, visual acuity, and pupil diameter.

Assessment of contrast sensitivity of patients with macular disease using reduced contrast near visual acuity charts

A set of near Bailey-Lovie logMAR letter charts that varied in contrast from 0.40 dB (C = 0.95) to 58.0 dB (C = 0.001) were used to measure the middle and high spatial frequency range of the contrast sensitivity function (CSF) of 15 subjects with age-related maculopathy (ARM) and 15 age-matched normal subjects. The letter charts were shown to have good test-retest reliability. Compared with measures made using CRT generated square wave gratings of variable contrast and spatial frequency they were also shown to provide a valid measure of CSF in the mid to high spatial frequency range. The 20.0 dB letter chart alone was shown to be a good screening device for macular disease. The letter charts do not provide a measure of the peak of the CSF and a supplementary test of contrast sensitivity is needed to quantify contrast sensitivity at a low spatial frequency. Three measures are proposed as necessary to document foveal visual capability of patients with macular disease: distance logMAR visual acuity to measure high spatial frequency resolution, visual acuity with letter charts of 20 dB contrast to assess mid spatial frequency resolution; and contrast sensitivity for the detection of an edge to estimate contrast sensitivity for larger objects.

An analysis of the fluid phase C1q binding assay. The effect of endogenous C1q on the precipitation and detection of an immune complex model

We examined the effect of endogenous C1q on the sensitivity of the fluid-phase C1q binding assay (C1qBA) in detecting an immune complex (IC) model, heat-aggregated IgG (HAIgG), at concentrations of 10-10,000 micrograms/ml sample. Results in normal human serum (NHS) or plasma (NHP) were compared with those in heat-inactivated NHS (NHS/56) in which most endogenous C1q was depleted by heat denaturation. Higher HAIgG concentrations were required in NHP and NHS to produce the same 125I-C1q precipitation seen in NHS/56. This decreased sensitivity varied from 70% at low HAIgG concentrations to 0% at high concentrations, as predicted for a large pool of endogenous C1q, in equilibrium with 125I-C1q, but in excess of that which could bind to all but the highest concentrations of IC model. In serum depleted of functional C1q on an immunoadsorbant of HAIgG, the precipitation of radiolabeled HAIgG under C1qBA conditions was concentration dependent and generated a saturation curve, showing that only a fraction of IC are usually precipitated in this assay. HAIgG precipitation was enhanced 1.4-fold in NHS/56 (8 micrograms C1q/ml) and three-fold in NHS (67 micrograms C1q/ml) suggesting that IC size is increased by endogenous C1q. In dual label experiments using 131I-HAIgG, the precipitation of 125I-C1q in NHS/56 was directly proportional to IC model precipitation, but markedly discordant in NHP, showing the measurement of IC in heat-inactivated sera superior to that in native serum. A comparison of the C1q:HAIgG ratio in PEG precipitates with that in samples, indicated that equilibrium was established between C1q and IC model. Thus the precipitation of 125I-C1q in the C1qBA represents (1) the fraction of total C1q bound to IC, and (2) the fraction of IC precipitated by PEG.

Reliability and validity of simple photographic plate tests of contrast sensitivity

Sets of edge and square wave grating photographic plates of varying contrasts were used to measure the mid to low spatial frequency range of the contrast sensitivity function (CSF) of 20 subjects with evident ocular disease and 20 age-matched normal subjects. Both plate tests were shown to have good test-retest reliability and to correlate well with electronic cathode ray tube (CRT) measures of CSF. The edge test, when administered in 2-dB steps of ascending contrast, has optimum sensitivity of 0.70 and specificity of 0.84 for detecting the patient with ocular disease with a fail criterion of less than 38 dB. A measure of edge contrast sensitivity was also shown to be a good predictor of the peak of the CSF, which is shown to be largely independent of the visual acuity of the subject. The 2 c/deg and 4 c/deg plates did not provide more information about the visual difficulties of subjects than the edge test. We advocate the use of an edge test as a simple clinical measure of low spatial frequency contrast sensitivity that provides information about visual dysfunction not provided by a measure of visual acuity.

Simulating refractive errors: source and observer methods

There are two principal methods of simulating refractive errors. Either the retinal image can be defocused by an optical system, usually a positive lens, placed in front of an observer's eye (observer method), or the source of the retinal image can be defocused as it is projected onto a screen or photograph (source method). There are significant differences between the two methods, differences that make it difficult to compare results. However, the source method, which is the more artificial, seems to be superior for a number of reasons. The results of these two methods can be compared using a common or interchangeable parameter for specifying the level of defocus. A convenient parameter is the size of the defocused image of a point, measured either in image space (linear or angular diameter on the retina) or in object space (angular diameter of the blur disc projected back into object space), with the angular diameter measured from the respective nodal point of the eye. Methods of measuring the angular blur-disc diameter for both methods are discussed and the validity of the formula omega = D delta L, is investigated, where omega is the angular diameter of the blur disc, D is the observer's pupil diameter, and delta L is the dioptric defocus.

Mechanisms of visual loss in corneal edema

Although visual disability from corneal edema is a well-recognized clinical finding, it is not easily confirmed by routine visual assessment. A more reliable assessment of visual changes resulting from corneal edema of varying origins is achieved by measurement of changes in the contrast sensitivity function. The measurements can be sensitized by the presence of a glare source to allow a more accurate determination of the nature of the visual loss. Even in the absence of a measurable loss of visual acuity, corneal edema leads to diminished visual function. The magnitude and type of this loss is dependent on the origin of the edema and the site of the corneal response.