- Email: [email protected]
Risk factors for non-communicable diseases in prison populations
Correspondence
British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK (JJVM); University of Texas Health Science Center, San Antonio, TX, USA (SMH); Duke Clinical Research Institute, Duke University, Durham, NC, USA (RMC); and Diabetes Trials Unit, Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford OX2 6HE, UK (RRH) 1
2
Tabák AG, Herder C, Rathmann W, Brunner EJ, Kivimäki M. Prediabetes: a high-risk state for diabetes development. Lancet 2012; 379: 2279–90. McMurray JJ, Holman RR, Haffner SM, et al, for the NAVIGATOR Study Group. Effect of valsartan on the incidence of diabetes and cardiovascular events. N Engl J Med 2010; 362: 1477–90.
Authors’ reply Arnaud Chiolero and Fred Paccaud note that prediabetes is not a unique disease entity and that the risk of diabetes is a continuum along blood glucose values. This comment highlights one important message of our paper—ie, the potential benefits of risk scores for diabetes risk prediction. In addition to blood glucose as a continuous risk factor for diabetes, risk prediction algorithms take into account other important modifiable risk factors such as hypertension, diet, or physical inactivity. There is, however, a need for further research because few studies have examined whether the use of risk calculators improves prediction of diabetes risk on the basis of current definitions of prediabetes. Chiolero and Paccaud also raise the issue of overdiagnosis and argue that population-wide intervention is a more rational strategy with which to prevent diabetes. In general, overdiagnosis happens if people are diagnosed with a disease that will never cause them symptoms or lead to loss of life. A wider definition includes changes in diagnostic thresholds that increase the use of drugs in otherwise healthy people. Both WHO and the American Diabetes Association emphasise that prediabetes is not a disease by itself. However, it is a state with a highly increased risk of conversion to diabetes. In the 20-year follow-up of the Da Qing trial,1 for example, almost 90% of participants progressed to type 2 1226
diabetes. We believe that, in the light of the current obesity and diabetes epidemic, both high-risk approaches targeted to prediabetic individuals and population-wide interventions targeted to all people are needed. Prakash Deedwania and Ali Ahmed raise an important point about the predictive value of prediabetes in cardiovascular events. In their study of older adults, prediabetes was not an independent risk factor for cardiovascular events. However, this finding contrasts with those of two metaanalyses2,3 that report an independent association between prediabetes and cardiovascular disease. We believe that differences in age distribution could partly explain this inconsistency. Until further confirmatory evidence becomes available, we suggest that prediabetes is taken mainly as a risk factor for diabetes and that cardiovascular risk is treated according to respective guidelines. John McMurray and colleagues note that valsartan was shown to reduce incident type 2 diabetes in their NAVIGATOR trial4 in people with prediabetes and an increased cardiovascular risk. We agree that there was a significant risk reduction of 14% (95% CI 8–20) between the group randomised to valsartan and the group that received other antihypertensive medication. However, we were concerned that the randomisation in that trial might have led to unintended differences between the study groups in terms of the use of diuretics and β blockers. These drugs have known diabetogenic effects, as pointed out by Luan.5 Indeed, in response to Luan’s comments, McMurray and colleagues adjusted their results for the difference in use of antihypertensive medication and found some attenuation of the risk reduction (13%, 95% CI 7–19). This finding suggests that valsartan might have been responsible for most but not all of the risk reduction seen in the trial.5 In light of this evidence, it seems that, for people with prediabetes and hypertension, an antihypertensive
regimen based on valsartan reduces the risk of incident type 2 diabetes but this reduction is modest compared with the effect of lifestyle intervention or metformin. MK is supported by the UK Medical Research Council, the US National Institutes of Health (R01HL036310, R01AG034454), and the Academy of Finland. We declare that we have no conflicts of interest.
*Adam G Tabák, Christian Herder, Wolfgang Rathmann, Eric J Brunner, Mika Kivimäki [email protected] Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK (AGT, EJB, MK); Semmelweis University Faculty of Medicine, 1st Department of Medicine, Budapest, Hungary (AGT); Institute of Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany (CH); and Institute for Biometry and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany (WR) 1
2
3
4
5
Li G, Zhang P, Wang J, et al. The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study. Lancet 2008; 371: 1783–89. Ford ES, Zhao G, Li C. Pre-diabetes and the risk for cardiovascular disease: a systematic review of the evidence. J Am Coll Cardiol 2010; 55: 1310–17. Sarwar N, Gao P, Seshasai SR, et al. Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: a collaborative meta-analysis of 102 prospective studies. Lancet 2010; 375: 2215–22. McMurray JJ, Holman RR, Haffner SM, et al, for the NAVIGATOR Study Group. Effect of valsartan on the incidence of diabetes and cardiovascular events. N Engl J Med 2010; 362: 1477–90. Luan FL. Effect of valsartan on the incidence of diabetes. N Engl J Med 2010; 363: 792–93.
Risk factors for noncommunicable diseases in prison populations The systematic review by Katharine Herbert and colleagues (May 26, p 1975)1 draws important attention to how female inmates in the American prison system are significantly more likely to be overweight and obese than are their peers in the general population. Prisons have provided opportunities for improving health care for some of the most vulnerable citizens in www.thelancet.com Vol 380 October 6, 2012
Correspondence
Katharine Herbert and colleagues1 did a systematic review of the prevalence of poor diet, inadequate physical activity, and overweight in prison populations worldwide. However, the literature search they adopted was not comprehensive enough to identify all eligible studies. Relevant data for this systematic review were more likely to be identified in government reports or official databases, which were not searched by Herbert and colleagues. By checking government websites and tracking the content of the included studies, we found that Herbert and colleagues missed at least four potentially eligible studies.2–5 These studies investigated inmate health in Australia, New Zealand, and Ireland, and could add important data such as bodyweight and physical activity to this systematic review. The possible ways to reduce missing studies in this systematic review are as follows: (1) search data from special websites for prison issues—eg, the Chinese prison network; (2) retrieve information from government reports or official databases; (3) track the background or discussion of similar studies; and (4) use internet search engines such as Google. We suggest that Herbert and colleagues do a supplementary literature search to see whether more studies could be included in this systematic review.
We declare that we have no conflicts of interest.
We declare that we have no conflicts of interest.
*Landon B Kuester, Timothy P Flanigan, Jennifer G Clarke, Adam Fletcher
Jin-Qiu Yuan, *Chen Mao, Jin-Ling Tang
[email protected]
[email protected]
Centre for Research on Drugs and Health Behaviour, London School of Hygiene and Tropical Medicine, University of London, London WC1H 9SH, UK (LBK, AF); Alpert Medical School of Brown University, Miriam Hospital, Providence, RI, USA (LBK, TPF); and Brown University Center for Primary Care and Prevention, Memorial Hospital of Rhode Island, Pawtucket, RI, USA (JGC)
School of Public Health and Primary Care, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
1
2
2
Herbert K, Plugge E, Foster C, Doll H. Prevalence of risk factors for noncommunicable diseases in prison populations worldwide: a systematic review. Lancet 2012; 379: 1975–82. Guerino PM, Harrison PM, Sabol W. Prisoners in 2010. Washington, DC: US Department of Justice, Bureau of Justice Statistics, 2011.
www.thelancet.com Vol 380 October 6, 2012
1
3
Herbert K, Plugge E, Foster C, Doll H. Prevalence of risk factors for noncommunicable diseases in prison populations worldwide: a systematic review. Lancet 2012; 379: 1975–82. Hannon F, Kelleher C, Friel S. General healthcare study of the Irish prisoner population. Dublin: Stationery Office, 2000. Ministry of Health. Results from the prisoner health survey 2005. Wellington: Ministry of Health, 2006. http://www.health.govt.nz/ publication/results-prisoner-healthsurvey-2005 (accessed Sept 17, 2012).
4
5
Epidemiology Branch, ACT Government Health Directorate. ACT inmate health survey 2010: summary results. Canberra: ACT Government, 2011. http://health.act.gov.au/health-services/ population-health/epidemiology-branch/ epidemiology-publications-health-series/ inmate-health-survey-summary-results (accessed Sept 17, 2012). Deloitte Consulting for the Department of Justice—Corrections Victoria. Victorian prisoner health study. Melbourne: Department of Justice—Corrections Victoria, 2003. http://www.justice.vic.gov.au/home/ prisons/research+and+statistics/ victorian+prisoner+health+study (accessed Sept 17, 2012).
Corbis
the USA (eg, free HIV screening and treatment); however, the increase in obesity and the harms associated with it are ignored. Research in the Rhode Island prison system has provided us with an insight into this problem in women’s prison facilities. There seem to be several drivers that explain Herbert and colleagues’ findings. First, limited space makes group exercise extremely difficult. Staffing shortages also cause frequent “lockdowns”, with digital television used to keep women occupied and immobile for extended periods. Second, budget reductions have resulted in a dependence on voluntary organisations for health programming, which tend not to focus on nutrition and exercise. Third, profit-driven food companies provide snack foods to inmates. Fourth, in the prison context, overeating provides a rare expression of control and choice, and in some cases drug and other addictions might be replaced by snack-food “addictions” which reduce anxiety and mitigate the effects of withdrawal and depression. These problems are not restricted to the female prison population. With about 1·6 million individuals in state and federal prisons, this represents a major public health blind spot.2 New interventions and policies should be developed and assessed to address the obesogenic nature of these institutions.
Authors’ reply We agree with Landon Kuester and colleagues that there is a need to develop and assess new interventions and policies to address the obesogenic nature of prisons. This should be regarded as a public health priority for these institutions globally. However, we disagree with Jin-Qiu Yuan and colleagues that the literature search we did was not sufficiently comprehensive. We adopted a search strategy that included the grey literature databases, including government sites. In this way we identified several of the Australian studies. We feel that some surveys might be relevant but not easily accessible without specialist support from academics within particular countries. From our own experience we have found that government documents or reports might be archived after a change of administration and can thus only be accessed by requests based on personal knowledge rather than a broad search strategy. We welcome Yuan and colleagues’ enthusiasm in pointing out these missing studies but are unsure how easily they could be found using a traditional and replicable systematic review approach. Most importantly, the additional studies do not change the key messages of our original paper; prisoners are at high risk of noncommunicable diseases and there is a dearth of evidence on this vulnerable group, particularly in low-income and middle-income countries. We declare that we have no conflicts of interest.
1227
British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK (JJVM); University of Texas Health Science Center, San Antonio, TX, USA (SMH); Duke Clinical Research Institute, Duke University, Durham, NC, USA (RMC); and Diabetes Trials Unit, Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford OX2 6HE, UK (RRH) 1
2
Tabák AG, Herder C, Rathmann W, Brunner EJ, Kivimäki M. Prediabetes: a high-risk state for diabetes development. Lancet 2012; 379: 2279–90. McMurray JJ, Holman RR, Haffner SM, et al, for the NAVIGATOR Study Group. Effect of valsartan on the incidence of diabetes and cardiovascular events. N Engl J Med 2010; 362: 1477–90.
Authors’ reply Arnaud Chiolero and Fred Paccaud note that prediabetes is not a unique disease entity and that the risk of diabetes is a continuum along blood glucose values. This comment highlights one important message of our paper—ie, the potential benefits of risk scores for diabetes risk prediction. In addition to blood glucose as a continuous risk factor for diabetes, risk prediction algorithms take into account other important modifiable risk factors such as hypertension, diet, or physical inactivity. There is, however, a need for further research because few studies have examined whether the use of risk calculators improves prediction of diabetes risk on the basis of current definitions of prediabetes. Chiolero and Paccaud also raise the issue of overdiagnosis and argue that population-wide intervention is a more rational strategy with which to prevent diabetes. In general, overdiagnosis happens if people are diagnosed with a disease that will never cause them symptoms or lead to loss of life. A wider definition includes changes in diagnostic thresholds that increase the use of drugs in otherwise healthy people. Both WHO and the American Diabetes Association emphasise that prediabetes is not a disease by itself. However, it is a state with a highly increased risk of conversion to diabetes. In the 20-year follow-up of the Da Qing trial,1 for example, almost 90% of participants progressed to type 2 1226
diabetes. We believe that, in the light of the current obesity and diabetes epidemic, both high-risk approaches targeted to prediabetic individuals and population-wide interventions targeted to all people are needed. Prakash Deedwania and Ali Ahmed raise an important point about the predictive value of prediabetes in cardiovascular events. In their study of older adults, prediabetes was not an independent risk factor for cardiovascular events. However, this finding contrasts with those of two metaanalyses2,3 that report an independent association between prediabetes and cardiovascular disease. We believe that differences in age distribution could partly explain this inconsistency. Until further confirmatory evidence becomes available, we suggest that prediabetes is taken mainly as a risk factor for diabetes and that cardiovascular risk is treated according to respective guidelines. John McMurray and colleagues note that valsartan was shown to reduce incident type 2 diabetes in their NAVIGATOR trial4 in people with prediabetes and an increased cardiovascular risk. We agree that there was a significant risk reduction of 14% (95% CI 8–20) between the group randomised to valsartan and the group that received other antihypertensive medication. However, we were concerned that the randomisation in that trial might have led to unintended differences between the study groups in terms of the use of diuretics and β blockers. These drugs have known diabetogenic effects, as pointed out by Luan.5 Indeed, in response to Luan’s comments, McMurray and colleagues adjusted their results for the difference in use of antihypertensive medication and found some attenuation of the risk reduction (13%, 95% CI 7–19). This finding suggests that valsartan might have been responsible for most but not all of the risk reduction seen in the trial.5 In light of this evidence, it seems that, for people with prediabetes and hypertension, an antihypertensive
regimen based on valsartan reduces the risk of incident type 2 diabetes but this reduction is modest compared with the effect of lifestyle intervention or metformin. MK is supported by the UK Medical Research Council, the US National Institutes of Health (R01HL036310, R01AG034454), and the Academy of Finland. We declare that we have no conflicts of interest.
*Adam G Tabák, Christian Herder, Wolfgang Rathmann, Eric J Brunner, Mika Kivimäki [email protected] Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK (AGT, EJB, MK); Semmelweis University Faculty of Medicine, 1st Department of Medicine, Budapest, Hungary (AGT); Institute of Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany (CH); and Institute for Biometry and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany (WR) 1
2
3
4
5
Li G, Zhang P, Wang J, et al. The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study. Lancet 2008; 371: 1783–89. Ford ES, Zhao G, Li C. Pre-diabetes and the risk for cardiovascular disease: a systematic review of the evidence. J Am Coll Cardiol 2010; 55: 1310–17. Sarwar N, Gao P, Seshasai SR, et al. Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: a collaborative meta-analysis of 102 prospective studies. Lancet 2010; 375: 2215–22. McMurray JJ, Holman RR, Haffner SM, et al, for the NAVIGATOR Study Group. Effect of valsartan on the incidence of diabetes and cardiovascular events. N Engl J Med 2010; 362: 1477–90. Luan FL. Effect of valsartan on the incidence of diabetes. N Engl J Med 2010; 363: 792–93.
Risk factors for noncommunicable diseases in prison populations The systematic review by Katharine Herbert and colleagues (May 26, p 1975)1 draws important attention to how female inmates in the American prison system are significantly more likely to be overweight and obese than are their peers in the general population. Prisons have provided opportunities for improving health care for some of the most vulnerable citizens in www.thelancet.com Vol 380 October 6, 2012
Correspondence
Katharine Herbert and colleagues1 did a systematic review of the prevalence of poor diet, inadequate physical activity, and overweight in prison populations worldwide. However, the literature search they adopted was not comprehensive enough to identify all eligible studies. Relevant data for this systematic review were more likely to be identified in government reports or official databases, which were not searched by Herbert and colleagues. By checking government websites and tracking the content of the included studies, we found that Herbert and colleagues missed at least four potentially eligible studies.2–5 These studies investigated inmate health in Australia, New Zealand, and Ireland, and could add important data such as bodyweight and physical activity to this systematic review. The possible ways to reduce missing studies in this systematic review are as follows: (1) search data from special websites for prison issues—eg, the Chinese prison network; (2) retrieve information from government reports or official databases; (3) track the background or discussion of similar studies; and (4) use internet search engines such as Google. We suggest that Herbert and colleagues do a supplementary literature search to see whether more studies could be included in this systematic review.
We declare that we have no conflicts of interest.
We declare that we have no conflicts of interest.
*Landon B Kuester, Timothy P Flanigan, Jennifer G Clarke, Adam Fletcher
Jin-Qiu Yuan, *Chen Mao, Jin-Ling Tang
[email protected]
[email protected]
Centre for Research on Drugs and Health Behaviour, London School of Hygiene and Tropical Medicine, University of London, London WC1H 9SH, UK (LBK, AF); Alpert Medical School of Brown University, Miriam Hospital, Providence, RI, USA (LBK, TPF); and Brown University Center for Primary Care and Prevention, Memorial Hospital of Rhode Island, Pawtucket, RI, USA (JGC)
School of Public Health and Primary Care, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
1
2
2
Herbert K, Plugge E, Foster C, Doll H. Prevalence of risk factors for noncommunicable diseases in prison populations worldwide: a systematic review. Lancet 2012; 379: 1975–82. Guerino PM, Harrison PM, Sabol W. Prisoners in 2010. Washington, DC: US Department of Justice, Bureau of Justice Statistics, 2011.
www.thelancet.com Vol 380 October 6, 2012
1
3
Herbert K, Plugge E, Foster C, Doll H. Prevalence of risk factors for noncommunicable diseases in prison populations worldwide: a systematic review. Lancet 2012; 379: 1975–82. Hannon F, Kelleher C, Friel S. General healthcare study of the Irish prisoner population. Dublin: Stationery Office, 2000. Ministry of Health. Results from the prisoner health survey 2005. Wellington: Ministry of Health, 2006. http://www.health.govt.nz/ publication/results-prisoner-healthsurvey-2005 (accessed Sept 17, 2012).
4
5
Epidemiology Branch, ACT Government Health Directorate. ACT inmate health survey 2010: summary results. Canberra: ACT Government, 2011. http://health.act.gov.au/health-services/ population-health/epidemiology-branch/ epidemiology-publications-health-series/ inmate-health-survey-summary-results (accessed Sept 17, 2012). Deloitte Consulting for the Department of Justice—Corrections Victoria. Victorian prisoner health study. Melbourne: Department of Justice—Corrections Victoria, 2003. http://www.justice.vic.gov.au/home/ prisons/research+and+statistics/ victorian+prisoner+health+study (accessed Sept 17, 2012).
Corbis
the USA (eg, free HIV screening and treatment); however, the increase in obesity and the harms associated with it are ignored. Research in the Rhode Island prison system has provided us with an insight into this problem in women’s prison facilities. There seem to be several drivers that explain Herbert and colleagues’ findings. First, limited space makes group exercise extremely difficult. Staffing shortages also cause frequent “lockdowns”, with digital television used to keep women occupied and immobile for extended periods. Second, budget reductions have resulted in a dependence on voluntary organisations for health programming, which tend not to focus on nutrition and exercise. Third, profit-driven food companies provide snack foods to inmates. Fourth, in the prison context, overeating provides a rare expression of control and choice, and in some cases drug and other addictions might be replaced by snack-food “addictions” which reduce anxiety and mitigate the effects of withdrawal and depression. These problems are not restricted to the female prison population. With about 1·6 million individuals in state and federal prisons, this represents a major public health blind spot.2 New interventions and policies should be developed and assessed to address the obesogenic nature of these institutions.
Authors’ reply We agree with Landon Kuester and colleagues that there is a need to develop and assess new interventions and policies to address the obesogenic nature of prisons. This should be regarded as a public health priority for these institutions globally. However, we disagree with Jin-Qiu Yuan and colleagues that the literature search we did was not sufficiently comprehensive. We adopted a search strategy that included the grey literature databases, including government sites. In this way we identified several of the Australian studies. We feel that some surveys might be relevant but not easily accessible without specialist support from academics within particular countries. From our own experience we have found that government documents or reports might be archived after a change of administration and can thus only be accessed by requests based on personal knowledge rather than a broad search strategy. We welcome Yuan and colleagues’ enthusiasm in pointing out these missing studies but are unsure how easily they could be found using a traditional and replicable systematic review approach. Most importantly, the additional studies do not change the key messages of our original paper; prisoners are at high risk of noncommunicable diseases and there is a dearth of evidence on this vulnerable group, particularly in low-income and middle-income countries. We declare that we have no conflicts of interest.
1227