Quality and Methodology Information

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1 21 July 2015 Issued by Offce for Natonal Statstcs, Government Buldngs, Cardff Road, Newport NP10 8XG Meda Offce Mortalty team Qualty and Methodology Informaton General detals Ttle of output: Alcohol-related deaths n the Unted Kngdom Desgnaton: Natonal Statstcs Geographc coverage: Unted Kngdom, England, Wales, Regons of England Date of last SQR or QMI : January 2012 Contact detals: mortalty@ons.gov.uk Executve summary Alcohol-related deaths n the Unted Kngdom presents statstcs on the number of deaths and the age-standardsed mortalty rates for deaths from alcohol-related causes. Alcohol-related deaths n the Unted Kngdom s compled usng nformaton suppled when a death s regstered. The number of deaths n England and Wales, and Englsh regons where the underlyng cause s consdered to be alcohol-related s extracted from ONS s Death Regstratons Database. Alcohol-related deaths n Scotland and Northern Ireland are publshed by Natonal Records of Scotland (NRS) and the Northern Ireland Statstcs and Research Agency (NISRA) respectvely. For the UK, the number of deaths and md-year populaton estmates for the 4 UK countres are combned and used to produce age-standardsed mortalty rates, standardsed usng the 2013 European Standard Populaton. Ths document contans the followng sectons: Output qualty About the output How the output s created Valdaton and qualty assurance Concepts and defntons Other nformaton, relatng to qualty trade-offs and user needs Sources for further nformaton or advce. Output qualty Ths document provdes a range of nformaton that descrbes the qualty of the data and detals any ponts that should be noted when usng the output. ONS has developed Gudelnes for Measurng Statstcal Qualty; these are based upon the 5 European Statstcal System (ESS) Qualty Dmensons. Ths document addresses these qualty dmensons and other mportant qualty characterstcs, whch are: Relevance Tmelness and punctualty 'Qualty and Methodology Informaton' (QMI) replaced 'Summary Qualty Reports' (SQR) from 04/11 1

2 Coherence and comparablty Accuracy Output qualty trade-offs Assessment of user needs and perceptons Accessblty and clarty More nformaton s provded about these qualty dmensons n the sectons below. About the output Relevance (The degree to whch statstcal outputs meet users needs) There s wdespread polcy, professonal and publc nterest n the prevalence of alcohol-related deaths n the UK, as excessve consumpton of alcohol s a major preventable cause of premature mortalty. It was estmated by the Government s Alcohol Strategy, 2012 to cost the NHS n England around 3.5 bllon each year. The man users of these statstcs nclude the Department of Health (DH) and devolved government admnstratons, publc health organsatons and local government. The fgures on alcohol-related deaths are used to montor and develop polces to protect the health of the general publc. In November 2010, the government publshed a Whte Paper ttled Healthy lves, healthy people: our strategy for publc health n England. It outlnes the government s commtment to protectng the populaton from serous health threats and helpng people to lve longer, healther and more fulfllng lves. Among other lfestyle and behavoural factors, the Whte Paper hghlghts the harmful effects of alcohol abuse and the assocated cost to the NHS. The Whte Paper ntroduced a Publc Health Responsblty Deal n whch publc, prvate and voluntary organsatons sgn up and work collaboratvely to address key publc health ssues, ncludng alcohol. Although the Whte Paper and the Responsblty Deal apply to England only, t s made clear that DH wll work closely wth the devolved admnstratons on areas of shared nterest. The Scottsh Government, the Welsh Government and the Northern Ireland Executve each have smlar alcohol polces. For example, the Scottsh Government publshes nformaton about mnmum prcng, mpact on health, drnkng culture, economc mpact, drnkng lmts and alcohol lcensng. Other users of these statstcs nclude health professonals, academcs and charty organsatons. The fgures are often used for research purposes and they are utlsed to target support servces for vulnerable groups. Tmelness and punctualty (Tmelness refers to the lapse of tme between publcaton and the perod to whch the data refer. Punctualty refers to the gap between planned and actual publcaton dates.) The provsonal date for the annual release of Alcohol-related deaths n the Unted Kngdom s announced on the ONS Release Calendar and.gov.uk webste 12 months n advance. The date s then fnalsed at least 1 month to publcaton. Alcohol-related deaths data are publshed n January or February each year (12 to 13 months after the end of the reference perod), followng the release of fnal annual death regstratons data and md-year populaton estmates for each consttuent country. Fgures are released around the same tme every year and have always been punctual. For more detals on related releases, the.gov.uk webste s avalable onlne and provdes 12 months advance notce of release dates. In the unlkely event of a change to the pre-announced 2

3 release schedule, publc attenton wll be drawn to the change and the reasons for the change wll be explaned fully at the same tme, as set out n the Code of Practce for Offcal Statstcs. How the output s created Alcohol-related deaths n the Unted Kngdom s compled usng nformaton suppled when a death s regstered. Informaton on deaths regstered n England and Wales s held on the ONS Death Regstratons Database whle those regstered n Scotland and Northern Ireland are held by NRS and NISRA respectvely. Further detals about the nformaton held on the ONS Death Regstratons Database, as well as the methods used to qualty assure the data, can be found n Mortalty Statstcs: Metadata. All deaths n England and Wales are coded by ONS accordng to the Internatonal Classfcaton of Dseases (ICD) produced by the World Health Organsaton. Alcohol-related deaths are defned usng the Nnth and Tenth Revson (ICD-9 and ICD-10 respectvely) of the ICD. Mortalty data for 1979 to 2000 are coded by ONS usng ICD-9 whle ICD-10 has been used snce Alcoholrelated deaths were defned usng the ICD codes n Box 1 n the Concepts and Defntons secton. The number of alcohol-related deaths splt by sex and age group (<1, 1-4, , 90 and over) for England and Wales (combned and separately) and Englsh regons, for the latest calendar year are extracted from ONS s Death Regstratons Database. These data are combned wth those for Scotland and Northern Ireland to produce statstcs for the UK. Mortalty rates are calculated usng the number of deaths and md-year UK populaton estmates provded by the Populaton Estmates Unt at ONS. Populaton estmates are based on the decennal UK census estmates and use nformaton on brths, deaths and mgraton to estmate the md-year populaton n non-census years. Further nformaton about the methods used to calculate md-year populaton estmates can be found n the Md-year populaton estmates short methods gude. The statstcal bulletn presents age-specfc and age-standardsed rates. The former are for the UK as a whole, whle the latter are for the UK, ts 4 consttuent countres and Englsh regons. Age-standardsed rates are calculated usng the drect method of standardsaton, whle the 2013 European Standard Populaton (ESP) s used as the standard populaton. Age-standardsed rates make allowances for the dfferences n the age structure of a populaton, over tme and between sexes. The age-standardsed rate for a partcular cause of death s that whch would have occurred f the observed age-specfc rates for that cause had appled n the gven standard populaton. Age-standardsed rates allow for dfferences n the age structure of populatons and therefore allow vald comparsons to be made between geographcal areas, the sexes and over tme. Agestandardsaton s carred out usng the drect method of standardsaton. In ths method, the agespecfc rates for each year are appled to a standard populaton structure to obtan the number of cases expected n each age group n the standard populaton. The numbers of expected cases are then added up across all age groups and dvded by the total standard populaton to obtan a summary rate fgure. A Mcrosoft Excel template whch demonstrates how age-standardsed rates and 95% confdence ntervals are calculated s avalable on ONS s webste. The ESP used n the prevous publcatons of alcohol-related deaths statstcs was frst ntroduced n 1976 but t s no longer representatve of the age-structure of the populaton of European Unon Member States. In lght of ths, Eurostat, the statstcal offce of the European Unon, mplemented a new verson of the ESP n ONS mplemented the 2013 ESP n 2014/15 fnancal year. The 2013 ESP takes nto account changes n the EU populaton, provdng a more current, methodologcally sound and wdely acceptable bass for the calculaton of age standardsed rates (Eurostat, 2013). The 1976 and 2013 ESPs dffer n 2 ways. Frst, the 2013 ESP gves the populatons n older age groups greater weghtng than the 1976 ESP. Second, the age dstrbuton of the 1976 ESP has an upper lmt of 85 years and over, whle the 2013 ESP s further dsaggregated to nclude age groups 85-89, and

4 Age-standardsed rates are calculated as follows: w r w 100,000 (expressed per 100,000 populaton) where: s the age group (<1, 1-4, 5-9, , 90+) w s the number, or proporton, of ndvduals n the standard populaton n age group r s the observed age-specfc rate n the subject populaton n age group, gven by: where: d r n d s the observed number of deaths n the subject populaton n age group n s the number of ndvduals n the subject populaton n age group Further nformaton about the mpact of changng the ESP on mortalty statstcs can be found on the ONS webste. ONS recommends the use of an abrdged verson of the ESP n the table wth an upper age lmt of 90+. Ths s because offcal populaton denomnators for the oldest age group n the ESP (95+) are not avalable for all geographcal area levels. Prevously publshed agestandardsed rates for 1994 to 2012 have been revsed n lght of the 2013 ESP. Rates for 1991 to 1993 have not been revsed due to a lack of offcal populaton denomnators for the oldest age group (90+) n the abrdged ESP for these years. Fgures for 1994 onwards are therefore not comparable wth those before The 2013 European Standard Populaton Age group (years) Populaton (number) Abrdged verson Under 1 1,000 1, ,000 4, ,500 5, ,500 5, ,500 5, ,000 6, ,000 6, ,500 6, ,000 7, ,000 7, ,000 7, ,000 7, ,500 6, ,000 6, ,500 5, ,000 5, ,000 4, ,500 2, ,500 1, and over and over Total 100, ,000 Source: Eurostat 4

5 Valdaton and qualty assurance Accuracy (The degree of closeness between an estmate and the true value.) The Natonal Statstcs defnton of alcohol-related deaths only ncludes those causes regarded as beng most drectly due to alcohol consumpton. The defnton allows for consstent comparsons over tme for those deaths most clearly assocated wth alcohol consumpton. It does not nclude other dseases where alcohol has been shown to have some causal relatonshp, such as cancers of the mouth, oesophagus and lver. Apart from deaths due to posonng wth alcohol (accdental, ntentonal or undetermned), other external causes of death, such as road traffc and other accdents, are also excluded. The defnton ncludes all deaths from chronc lver dsease and crrhoss (excludng blary crrhoss), even when alcohol s not specfcally mentoned on the death certfcate. Despte ths, the actual number of alcohol deaths n each year s lkely to be greater than those reported n the bulletn. Ths s because the causal relatonshp between alcohol and causes of death such as mouth cancer and road traffc accdents may be dffcult to establsh. Mortalty statstcs acheve 100% coverage, as t s a legal requrement that all deaths are regstered. However, n some cases the regstraton of a death may not take place n the same calendar year as the death occurred. Ths s most lkely to occur n cases where the death s referred to a coroner and an nquest s held. Deaths are referred to a coroner n cases ncludng where the cause of death s unknown, where the deceased was not seen by a doctor before or after death or where the death was volent, unnatural or suspcous. If the coroner chooses to hold an nquest, the death can only be regstered once the nquest has taken place. The accuracy of mortalty statstcs s dependent on the qualty of nformaton suppled when the death s regstered. An ncorrect underlyng cause of death may be provded by the doctor completng the death certfcate. Many thousands of practsng doctors complete death certfcates and the nature and amount of tranng they have had n death certfcaton vares greatly. Inaccurate nformaton may also be suppled by the nformant (usually a relatve of the deceased) who must use the death certfcate to regster the death wth the regstrar. It s not possble to measure the magntude of errors such as these. Further nformaton about the process nvolved n death regstraton and the checks carred out on the data held by ONS to ensure ther qualty can be found n Mortalty Statstcs: Metadata. Rates were not calculated where there were fewer than 3 deaths n a cell for age-specfc rates or 10 deaths n a year for age-standardsed rates. It s ONS practce not to calculate rates based on such small numbers, as they are mprecse and susceptble to naccurate nterpretaton. Agestandardsed rates based on 10 to 19 deaths are marked wth a u to warn users that ther relablty s low. Rates are publshed wth 95% confdence ntervals (CIs) to allow users to dentfy sgnfcant dfferences between geographcal areas, the sexes and over tme. Sgnfcance s assgned on the bass of non-overlappng CIs. Whle more formalsed and accurate methods of sgnfcance testng are avalable, the non-overlappng CI method s used because t s both smple to calculate and easly understood. The methods used n prevous bulletns to calculate standard errors and 95% CIs have now been modfed. Data from 2013 onwards wll now be based on the methods descrbed below. Standard error In prevous publcatons, the standard error for age-standardsed rates was calculated usng a smple approxmaton method as shown below. The standard error s denoted as SE(ASR) and calculated as: SE( ASR) ASR N where: ASR s the age-standardsed rate N s the total number of deaths n all age groups n each year 5

6 The age-standardsed rate s a weghted sum of age-specfc death rates where the age-specfc weghts represent the relatve age dstrbuton of the standard populaton (n ths case the 2013 ESP). Therefore, t s more accurate to calculate ts varance as the sum of the age-specfc varances and to estmate ts standard error as the square root of the varance as shown below. SE ( ASR) 2 r w d w 2 2 where: w s the number of ndvduals n the standard populaton n age group r s the crude age-specfc rate n the local populaton n age group d s the number of deaths n the local populaton n age group The standard error calculaton has now been modfed so that t takes nto account the varance of the weghted sum of age-specfc rates. Confdence ntervals The mortalty data n ths release are not subject to samplng varaton as they were not drawn from a sample. Nevertheless, they may be affected by random varaton, partcularly where the number of deaths or probablty of dyng s small. To help assess the varablty n the rates, they have been presented alongsde 95% CIs. The choce of the method used n calculatng confdence ntervals for rates wll, n part, depend on the assumptons made about the dstrbuton of the deaths data these rates are based on. Tradtonally, a normal approxmaton method has been used to calculate confdence ntervals on the assumpton that alcohol-related deaths are normally dstrbuted. However, f the annual number of alcohol-related deaths s relatvely small (fewer than 100), t may be assumed to follow a Posson probablty dstrbuton. In such cases, t s more approprate to use the confdence lmt factors from a Posson dstrbuton table to calculate the confdence ntervals nstead of a normal approxmaton method. The method now used n calculatng confdence ntervals for rates based on fewer than 100 deaths was proposed by Dobson et al., (1991) as descrbed n APHO, (2008). In ths method, confdence ntervals are obtaned by scalng and shftng (weghtng) the exact nterval for the Posson dstrbuted counts (number of deaths n each year). The weght used s the rato of the standard error of the age-standardsed rate to the standard error of the number of deaths. The lower and upper 95% CIs are denoted as ASR lower and ASR upper, respectvely, and calculated as: ASR lower ASR ( D l D) v( ASR) v( D) Where: ASR upper ASR ( D u D) v( ASR) v( D) D l and D u are the exact lower and upper confdence lmts for the number of deaths, calculated usng confdence lmt factors from a Posson probablty dstrbuton table D s the number of deaths n each year v(asr) s the varance of the age-standardsed rate v(d) s the varance of the number of deaths 6

7 Where there are 100 or more deaths n a year the 95% confdence ntervals for age-standardsed rates are calculated usng the normal approxmaton method shown below: Where: ASR LL / UL ASR SE ASR LL/UL represents the upper and lower 95% confdence lmts, respectvely, for the agestandardsed rate Age-specfc rates For age-specfc rates, the exact Posson lmt factors for the number of deaths s multpled by the rate to calculate the 95% confdence ntervals where there are fewer than 100 deaths n a partcular age group. LL(R) = L R and UL(R) = U R Conversely, the normal approxmaton method below s used where there are 100 or more deaths. Where: R LL / UL R R N LL and UL are the lower and upper 95% confdence lmts, respectvely R s the age-specfc rate L and U are the exact lower and upper Posson confdence lmt factors for the age-specfc number of deaths Coherence and comparablty (Coherence s the degree to whch data that are derved from dfferent sources or methods, but refer to the same topc, are smlar. Comparablty s the degree to whch data can be compared over tme and doman for example, geographc level.) Alcohol-related death statstcs are based on death regstratons data. Data for England and Wales are held by ONS and data for Scotland and Northern Ireland are suppled by the NRS, formerly the General Regster Offce for Scotland (GROS), and NISRA respectvely. Informaton on death regstraton processes n each country can be found n the followng lnks: England and Wales Scotland Northern Ireland Deaths of non-resdents are ncluded n the fgures for England and Wales combned, but excluded for England and Wales when presented separately. Therefore, the sum of the number of deaths n England and Wales separately does not equal the fgure for England and Wales combned. In the UK, causes of death are coded accordng to the ICD produced by WHO. The Nnth Revson of ICD was used n Scotland untl 1999 and n England and Wales and Northern Ireland untl The Tenth Revson has snce been n use. Consequently, for the year 2000, results for Scotland are not drectly comparable wth those for other UK countres. ONS has revsed the md-2002 to 2010 populaton estmates for the UK and ts consttuent countres n lght of the 2011 Census. Consequently, alcohol-related death rates relatng to ths perod have now been revsed. Alcohol-related death statstcs are not currently produced for areas smaller than regons as there are too few deaths to produce statstcally robust rates. A one-off study was carred out by ONS n 2007 to calculate age-standardsed rates for local areas n the UK usng data aggregated over the perods and More nformaton on that study s avalable n an artcle ttled Trends and geographcal varatons n alcohol-related deaths n the Unted Kngdom, and accompanyng data are avalable on the ONS webste. Wth the excepton of year 2000, fgures for ndvdual UK countres have been calculated usng consstent methods and defntons over tme and are therefore comparable. 7

8 Internatonally, WHO has developed the WHO Global Informaton System on Alcohol and Health whch contans several ndcators to allow alcohol consumpton and the effects of consumpton, ncludng mortalty, to be compared on an nternatonal bass across contnents. The agestandardsed mortalty rates produced by WHO dffer from those produced by ONS n 3 ways: frstly, only deaths from lver crrhoss and road traffc accdents are ncluded n WHO s alcoholrelated deaths defnton whle 12 causes of death are ncluded n ONS s defnton (see Box 1) secondly, the age-standardsed mortalty rates presented by WHO are standardsed usng the World Standard Populaton, whle ONS s uses the European Standard Populaton thrdly, the WHO s age-standardsed mortalty rates are based on those aged 15 years and over whle ONS s rates are based on persons at all ages The age-standardsed alcohol-related death rates publshed by the WHO and ONS are therefore not comparable. Concepts and Defntons (Concepts and defntons descrbe the legslaton governng the output and a descrpton of the classfcatons used n the output.) ICD - the Internatonal Classfcaton of Dseases s the standard dagnostc tool for epdemology, health management and clncal purposes. It s used to classfy dseases and other health problems recorded on many types of health and vtal records ncludng death certfcates and health records. In addton to enablng the storage and retreval of dagnostc nformaton for clncal, epdemologcal and qualty purposes, these records also provde the bass for the complaton of natonal mortalty and morbdty statstcs by WHO Member States. It s used for rembursement and resource allocaton decson-makng by countres. The tenth revson has been used by ONS snce Underlyng cause - defned by WHO as the dsease or njury whch ntated the tran of morbd events leadng drectly to death, or the crcumstances of the accdent or volence whch produced the fatal njury, n accordance wth the rules of the Internatonal Classfcaton of Dseases. The defnton used to comple statstcs on alcohol-related deaths across the UK s shown n Box 1. Ths defnton ncludes only those causes regarded as beng most drectly due to alcohol consumpton. It does not nclude deaths due to other dseases where alcohol has been shown to have some causal relatonshp, such as cancers of the mouth, oesophagus and lver. The defnton ncludes all deaths from chronc lver dsease and crrhoss (excludng blary crrhoss), even when alcohol s not specfcally mentoned on the death certfcate. Apart from deaths due to posonng wth alcohol (accdental, ntentonal or undetermned), ths defnton excludes any other external causes of death, such as road traffc and other accdents. The defnton allows for consstent comparsons over tme for those deaths most clearly assocated wth alcohol consumpton. 8

9 Box 1: Natonal Statstcs defnton of alcohol-related deaths Internatonal Classfcaton of Dseases, Nnth Revson (ICD-9) 291 Alcoholc psychoses 303 Alcohol dependence syndrome Non-dependent abuse of alcohol Alcoholc cardomyopathy 571 Chronc lver dsease and crrhoss (Excludng Blary crrhoss) E860 Accdental posonng by alcohol Internatonal Classfcaton of Dseases, Tenth Revson (ICD-10) F10 Mental and behavoural dsorders due to use of alcohol G31.2 Degeneraton of nervous system due to alcohol G62.1 Alcoholc polyneuropathy I42.6 Alcoholc cardomyopathy K29.2 Alcoholc gastrts K70 Alcoholc lver dsease K73 Chronc hepatts, not elsewhere classfed K74 Fbross and crrhoss of lver (Excludng K74.3 K74.5 Blary crrhoss) K86.0 Alcohol nduced chronc pancreatts X45 Accdental posonng by and exposure to alcohol X65 Intentonal self-posonng by and exposure to alcohol Y15 Posonng by and exposure to alcohol, undetermned ntent Informaton about deaths regstered s 100% complete snce t s a legal requrement that all deaths are regstered. The legslaton that requres ths s the Brths and Deaths Regstraton Act (1836) whch came nto force from 1 July Other nformaton Output Qualty Trade-Offs (Trade-offs are the extent to whch dfferent dmensons of qualty are balanced aganst each other.) Alcohol-related deaths n the Unted Kngdom s publshed 12 months after the reference perod. The producton of these statstcs reles upon the avalablty of the annual deaths regstratons data for each consttuent country of the UK as well as the UK md-year populaton estmates produced by ONS. Codng and qualty assurance of death regstraton data s tme consumng and fnal fgures for the whole of the UK are not avalable untl 12 months after the reference perod. For t to be publshed earler, provsonal data would need to be used and would need to be subsequently revsed. Users have not ndcated that they are unhappy wth ths balance between tmelness and qualty. In England and Wales, deaths should be regstered wthn 5 days of the death occurrng, but there are some stuatons that result n the regstraton of the death beng delayed. Deaths consdered unexpected, accdental or suspcous wll be referred to a coroner who may order a post mortem or carry out a full nquest to ascertan the reasons for the death. Statstcs on alcohol-related deaths are presented based on the year these deaths were regstered rather than the year of occurrence. Ths method s used because there s a requrement for consstent and tmely data, despte a potental lmtaton n data qualty caused by regstraton delays. The majorty of alcohol-related deaths regstered n a partcular year also occur n that year so the mpact of regstraton delays on these statstcs are consdered to be neglgble. Further nformaton on the mpact of regstraton delays on mortalty statstcs s avalable on the ONS webste. 9

10 Sources for further nformaton or advce Accessblty and Clarty (Accessblty s the ease wth whch users are able to access the data, also reflectng the format n whch the data are avalable and the avalablty of supportng nformaton. Clarty refers to the qualty and suffcency of the release detals, llustratons and accompanyng advce.) ONS's recommended format for accessble content s a combnaton of HTML webpages for narratve, charts and graphs, wth data beng provded n usable formats such as CSV and Excel. The ONS webste also offers users the opton to download the narratve n PDF format. In some nstances other software may be used, or may be avalable on request. Avalable formats for content publshed on the ONS webste but not produced by the ONS, or referenced on the ONS webste but stored elsewhere, may vary. For further nformaton please refer to the contact detals at the begnnng of ths document. For nformaton regardng condtons of access to data, please refer to the lnks below: Terms and condtons (for data on the webste) Copyrght and reuse of publshed data Pre-release access (ncludng condtons of access) Access to mcrodata va the Vrtual Mcrodata Laboratory Accessblty In addton to ths Qualty and Methodology Informaton, Basc Qualty Informaton relevant to each release s avalable n the background notes of the relevant Statstcal Bulletn. 10