Roger Harrison

Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review.

Abstract Objective To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer. Data sources Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies. Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate. Results Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded. Conclusion Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Smoking and age-related macular degeneration: A review of association

PurposeAge-related macular degeneration (AMD) is the leading cause of severe and irreversible vision loss in the Western world. As there is no effective treatment for all types of AMD, identifying modifiable risk factors is of great importance. This review evaluates the epidemiological evidence associating smoking with AMD.MethodsSystematic review of published epidemiological studies evaluated against established criteria for evidence of a causal relationship.ResultsIn total, 17 studies (cross-sectional studies, prospective cohort studies, and case–control studies) were included in the review. A total of 13 studies found a statistically significant association between smoking and AMD with increased risk of AMD of two- to three-fold in current-smokers compared with never-smokers. Five studies found no association between smoking and AMD. There was also evidence of dose-response, a temporal relationship and reversibility of effect.ConclusionThe literature review confirmed a strong association between current smoking and AMD, which fulfilled established causality criteria. Cigarette smoking is likely to have toxic effects on the retina. In spite of the strength of this evidence, there appears to be a lack of awareness about the risks of developing eye disease from smoking among both healthcare professionals and the general public.

Cigarette smoking and thyroid eye disease : a systematic review

PurposeTo evaluate the epidemiological evidence for a causal association between tobacco smoking and thyroid eye disease (TED).MethodsSystematic review, including quality assessment, of published epidemiological studies and evaluation of the evidence using established causality criteria.ResultsFourteen papers describing 15 studies were included. There was a positive association between smoking and TED in four case–control studies when compared with control patients with Graves’ disease but no ophthalmopathy (odds ratio (OR) 1.94–10.1) and in seven case–control studies in which control subjects did not have thyroid disease (OR 1.22–20.2). Two cohort studies examined the occurrence of new cases of TED; one study found an increased incidence of TED with smoking. Four cohort studies investigated progression or outcome of treatment in patients with established TED, three finding an association between smoking and poorer outcome. The quality of the studies was variable, but the association with smoking was strong in the most methodologically rigorous studies. Other evidence supporting a causal link was a consistent association across studies, a dose–response effect, a reduced risk of TED in ex-smokers, and a temporal relationship.ConclusionThis systematic review provided strong evidence for a causal association between smoking and development of TED. Current-smokers were also more likely to experience disease progression or poorer outcome of treatment. Patients with Graves’ disease and the general public should be educated about the risk of smoking and TED. These findings suggest that patients with Graves’ disease or TED who are smokers should be given effective support to stop smoking.

The population effect of crime and neighbourhood on physical activity: an analysis of 15 461 adults

Area-based interventions offer the potential to increase physical activity for many sedentary people in countries such as the UK. Evidence on the effect of individual and area/neighbourhood influences on physical activity is in its infancy, and despite its value to policy makers a population focus is rarely used. Data from a population-based health and lifestyle survey of adults in northwest England were used to analyse associations between individual and neighbourhood perceptions and physical activity. The population effect of eliminating a risk factor was expressed as a likely effect on population levels of physical activity. Of the 15 461 responders, 21 923 (27.1%) were physically active. Neighbourhood perceptions of leisure facilities were associated with physical activity, but no association was found for sense of belonging, public transport or shopping facilities. People who felt safe in their neighbourhood were more likely to be physically active, but no associations were found for vandalism, assaults, muggings or experience of crime. The number of physically active people would increase by 3290 if feelings of “unsafe” during the day were removed, and by 11 237 if feelings of “unsafe” during the night were removed. An additional 8342 people would be physically active if everyone believed that they were “very well placed for leisure facilities”. Feeling safe had the potential largest effect on population levels of physical activity. Strategies to increase physical activity in the population need to consider the wider determinants of health-related behaviour, including fear of crime and safety.

Smoking and cataract: review of causal association.

&NA; Several risk factors for the development of cataract have been identified. This review evaluates epidemiologic literature that has examined tobacco smoking as a risk factor for cataract formation using established causality criteria. Twenty‐seven studies were included in this review. Evidence suggests that smoking has a 3‐fold increase on the risk for incident nuclear cataract development. There was also evidence of dose response, temporal relationship, and reversibility of effect. There was limited evidence of an association between smoking and posterior subcapsular cataract, but little or no association with cortical cataract. Thus, the literature review indicated a strong association between smoking and the development of cataract, particularly nuclear cataract. The association fulfills the established criteria for causality. The association between smoking and other types of cataract is less distinct and requires further evaluation.

Who and how many people are taking herbal supplements? A survey of 21,923 adults.

BACKGROUND There is little information on the number and characteristics of adults taking herbal supplements and the relationship of this with other health and lifestyle factors. These were examined in the current study. METHODS Information on herbal supplement use and health and lifestyle characteristics was obtained by postal questionnaire, sent to a sample of the adult population in Northwest England. RESULTS In summer 2001, 70.5% (15,465/21,923) of questionnaires were returned. The mean age of responders was 49.8 years (SD 17.57) and 45.2% (6,986/15,465) were men. The percentage taking at least one herbal supplement was 12.8% (1,987/15,465). Users of herbal supplements were more likely to be younger, female, white, and to own their home. Herbal supplement use was not strongly associated with any health and lifestyle variables examined. Weak associations were found with physical activity, psychiatric caseness, and use of prescribed medications. The most common herbal supplement was evening primrose oil, taken by 7.7% (1,186/15,465) of respondents (12.7% of women and 1.1% of men). CONCLUSIONS More than one in ten adults were taking herbal supplements, with evening primrose oil, the most common supplement, used mainly by women. Individual characteristics such as age, sex, ethnicity, and social class influenced the use of herbal supplements, but there was no evidence that this substituted for conventional medical care. The evidence base to support some popular herbal supplements is weak. Large well-designed trials are needed to quantify the value of herbal supplements to health and well-being.

Cigarette smoking and primary open angle glaucoma: a systematic review.

PurposeTo evaluate the epidemiologic evidence for a causal association between tobacco smoking and primary open angle glaucoma (POAG). MethodsSystematic review, including quality assessment, of published analytical epidemiologic studies and evaluation of the evidence using established causality criteria (strength, consistency, temporality, dose response, reversibility, and biologic plausibility). ResultsEleven papers describing 9 case-control studies, 1 prospective cohort study, and a paper describing a pooled analysis based on 2 prospective cohort studies were included in the review. The methodologic quality of most included studies was poor. The strongest studies methodologically were the cohort studies on which the pooled analysis was based. Neither the prospective cohort study (rate ratio not reported) nor the pooled analysis of 2 prospective cohort studies (adjusted rate ratio 0.9) found an association between smoking and POAG. There was a significant positive association between smoking and POAG in only 2 of the case-control studies (adjusted odds ratio 2.9 and 10.8). There was no evidence of a dose-response relationship with smoking or of reversibility of effect in the studies where this was assessed. ConclusionsThis systematic review provided little evidence for a causal association between smoking and development of POAG. Given the limited evidence from high quality studies, and the possibility that flaws in many of the studies reviewed biased the results toward the null, further high quality research to confirm our conclusions is needed. However, it remains important to warn ophthalmic patients of the dangers of smoking and provide cessation support owing to the clear evidence of links between smoking and other ocular and systemic diseases.

Increasing response to a postal survey of sedentary patients – a randomised controlled trial [ISRCTN45665423]

BackgroundA systematic review identified a range of methods, which can influence response rates. However, analysis specific to a healthcare setting, and in particular, involving people expected to be poor responders, was missing, We examined the effect of pre-warning letters on response rates to a postal survey of sedentary patients whom we expected a low rate of response.MethodsParticipants were randomised to receive a pre-warning letter or no pre-warning letter, seven days before sending the main questionnaire. The main questionnaire included a covering letter and pre-paid return envelope. After seven days, non-responders were sent a reminder letter and seven days later, another reminder letter with a further copy of the questionnaire and return envelope.Results627 adults, with a mean age of 48 years (SD 13, range 18 to 78) of whom 69.2% (434/627) were women, were randomised. 49.0% (307/627) of patients were allocated to receive a pre-warning letter and 51.0% (320/627) no pre-warning letter, seven days in advance of posting the main questionnaire. The final response rate to the main questionnaire was 30.0% (92/307) amongst those sent a pre-warning letter and 20.9% (67/320) not sent a pre-warning letter, with an adjusted odds ratio of 1.60 (95% CI 1.1, 2.30).ConclusionsThe relatively low cost method of sending a pre-warning letter had a modest impact on increasing response rates to a postal questionnaire sent to a group of patients for whom a low response rate was anticipated. Investigators should consider incorporating this simple intervention when conducting postal surveys, to reduce the potential for nonresponse bias and to increase the study power. Methods other than postal surveys may be needed however when a low response rate to postal surveys is likely.

Perceptions of blindness related to smoking: a hospital-based cross-sectional study

AimsSmoking is associated with several serious eye diseases. Awareness of smoking and blindness, and its potential to act, as a stimulus to assist stopping smoking has not been investigated.MethodsA cross-sectional survey using a structured interview of adult patients attending district general hospital ophthalmology, general surgery, and orthopaedic clinics. The interview investigated the awareness and fear of blindness for three established smoking-related diseases, and a distractor condition (deafness), and the likelihood that smokers would quit on developing early signs of each condition.ResultsResponse was 89.1% (358/402). In all, 183 (51.1%) of responders were male and 175 (48.9%) female. Only 9.5% of patients believed that smoking was definitely or probably a cause of blindness, compared with 92.2% for lung cancer, 87.6% for heart disease, and 70.6% for stroke. Patients ranked their fear of each of the five conditions, scoring five for the most feared and one for the least feared. Patients were significantly (P<0.01) less fearful of blindness (mean score 2.80) than lung cancer (3.89), heart disease (3.58), and stroke (3.35). About one-half of smokers stated that they would definitely or probably quit smoking if they developed early signs of blindness or the three established smoking-related conditions, with no significant differences in proportions for these four conditions.ConclusionThe findings suggest that awareness of the risk of blindness from smoking is low, but that the fear of blindness is as compelling a motivation to quit as fear of lung cancer, heart disease, and stroke. The link between smoking and eye disease should be publicised to help reduce smoking prevalence.

Teenagers’ perceptions of blindness related to smoking: a novel message to a vulnerable group

Background: Cigarette smoking often starts in teenage years. It is not known whether teenagers are aware of the association of smoking with eye disease and blindness. Aim: To explore the knowledge of the link between smoking, and eye diseases and blindness, and the likely impact of this knowledge among teenagers in UK. Methods: A cross-sectional survey, using a structured interview of teenagers attending four organised social events, was conducted. Awareness and fear of blindness, and of three smoking-related diseases (lung cancer, heart disease and stroke) and a distractor condition (deafness) was investigated. The likelihood of smokers quitting on developing early signs of each condition was determined. Results: A 92% “opt in” response rate was achieved. Out of 260 teenagers (16–18 years), 15%, 27% and 81% believed that smoking caused stroke, heart disease and lung cancer, respectively. Only 5% believed smoking caused blindness. Subjects ranked their fear of each of the five conditions, scoring five for the most feared and one for the least feared. Subjects were significantly (p<0.01) more fearful (mean scores in brackets) of blindness (4.2) than of lung cancer (3.4), heart disease (2.3) and deafness (1.2). More teenagers (p<0.01) said they would stop smoking on developing early signs of blindness compared with early signs of lung or heart disease. Conclusions: Awareness of the risk of blindness from smoking is low among teenagers, but fear of blindness may be more likely to motivate teenagers to stop smoking than fear of lung or heart disease. Teenagers should be made more aware of the ocular risks of cigarette smoking as a novel public health measure.