Yates, Megan Amy (2018) Inequalities in mortality amenable to healthcare intervention in Scotland. PhD thesis. https://theses.gla.ac.uk/30905/ Copyright and moral rights for this work are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Enlighten: Theses https://theses.gla.ac.uk/ [email protected] INEQUALITIES IN MORTALITY AMENABLE TO HEALTHCARE INTERVENTION IN SCOTLAND MEGAN AMY YATES MPH, BSC (HONS) SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy MRC/CSO SOCIAL AND PUBLIC HEALTH SCIENCES UNIT INSTITUTE OF HEALTH AND WELLBEING COLLEGE OF MEDICAL,VETERINARY AND LIFE SCIENCES UNIVERSITY OF GLASGOW DECEMBER 2017 © MEGAN AMY YATES 2 Abstract Mortality amenable to health care intervention are premature deaths which, theoretically, should not occur in the presence of timely and effective health care. As Scotland has a universal health care system, where health care is freely provided at the point of access to all residents, there should be no socioeconomic inequalities in rates of amenable mortality (AM). However, gradients in rates of AM have been found in many countries, using various measures of socioeconomic position. The routine monitoring of rates of AM, and subgroups of amenable conditions, will contribute towards an indicator of health care performance. Records of all deaths occurring between 1980 and 2013, records of hospitalisations for amenable conditions, and mid-year population estimates were used to calculate rates of age standardised mortality and incident hospitalisations respectively. Absolute and relative in- equalities in both rates for the total population were estimated using an area based measure of material deprivation, the Carstairs index. Individual level measurements of socioeco- nomic position, such as educational attainment, were used to measure inequalities in rates of deaths for a sample of the population, allowing for some comparison with European coun- tries. Rates of AM in Scotland and England were compared in two natural experiments in the final two chapters, aiming to explore the direct and indirect effects of policy changes on health care systems abilities to effectively prevent amenable deaths. Rates of AM in Scotland have been found to be decreasing for both men and women. Mor- tality rates within two of the three subgroups of amenable conditions have also declined, with the third having too few deaths to comment on trends. The rates of incident hospi- talisations of amenable conditions between 1996 and 2013 have remained relatively stable, suggesting that rates of AM may be reflecting improvements in the detection, treatment, and management of amenable conditions. Absolute and relative inequalities in mortality rates were largest when estimated using educational attainment, whilst occupational measures produced the smallest inequalities. The rate of decline in rates of AM slowed in Scotland, relative to England, following devolution, however the attempts to adequately control for differing levels of deprivation were unsuccessful. The final chapter saw step increase in rates of AM in England, compared to Scotland, following the publication of a White Paper for the Health and Social Care Act - however, this failed to reach statistical significance. This thesis concludes that the continued study of amenable mortality in Scotland is worth- while, given that mortality rates continued to decline against stable rates of incident hospi- talisations, and relative inequalities in mortality rates were found to be increasing, despite decreasing absolute inequalities. The monitoring of inequalities in rates of AM provides the potential for weaknesses in the provision and delivery of care to be identified and corrected. 3 Table of Contents 1 Introduction 31 1.1 Aims and Objectives . 32 1.2 Thesis structure . 32 1.3 Terminology . 34 2 Literature Review 36 2.1 Search Strategy . 36 2.2 Overview of studies . 38 2.3 The concept of ‘amenable mortality’: History and evolution . 38 2.3.1 Definition of amenable mortality . 40 2.3.2 Distinction between avoidable and amenable mortality . 42 2.3.3 Further categorisations . 44 2.3.4 Choice of amenable conditions . 46 2.3.5 Age limits . 50 2.4 Applications . 51 2.4.1 Europe . 53 2.4.2 Americas . 71 Table of Contents 4 2.4.3 Australasia . 77 2.4.4 Asia . 82 2.4.5 Africa . 85 2.4.6 International studies . 85 2.4.7 Inequalities in rates of amenable mortality . 92 2.5 Chapter Summary . 95 2.5.1 Questions arising from the literature review . 95 3 General Methods 97 3.1 Introduction . 97 3.2 Choice of conditions amenable to medical intervention . 97 3.2.1 Ischaemic heart disease, cerebrovascular disease and diabetes mellitus 101 3.3 Data sources . 102 3.3.1 Outcomes . 102 3.3.2 Population . 102 3.3.3 Numerator-denominator bias . 104 3.4 Age Standardised Rates . 104 3.5 Area based measures of deprivation . 105 3.5.1 Carstairs Index . 106 3.5.2 Scottish Index of Multiple Deprivation . 107 3.5.3 Comparison between the Carstairs index and SIMD . 108 3.6 Poisson Regression . 111 3.7 Measures of inequality . 111 Table of Contents 5 3.8 Fractional Polynomials . 114 3.9 Multilevel modelling . 115 3.10 Software . 117 3.11 Ethical and Data Access Approval . 118 4 Amenable mortality in Scotland 120 4.1 Introduction . 120 4.2 Objectives . 121 4.3 Methods . 122 4.3.1 Data . 122 4.3.2 Assigning deprivation indices . 122 4.3.3 Statistical Analyses . 123 4.3.4 Sensitivity Analyses . 127 4.4 Results . 128 4.4.1 Data cleaning and descriptive statistics . 128 4.4.2 Age standardised amenable mortality rates . 131 4.4.3 Indices of inequality . 142 4.4.4 Fractional polynomials . 145 4.4.5 Multilevel Modelling . 151 4.4.6 Sensitivity analyses . 162 4.5 Discussion . 172 4.5.1 Principal findings . 172 4.5.2 Strengths and limitations . 175 Table of Contents 6 4.5.3 Relations to other studies . 176 4.5.4 Research implications . 178 4.5.5 Next steps . 178 5 Incidence of amenable conditions in Scotland 179 5.1 Introduction . 179 5.2 Objectives . 180 5.3 Methods . 181 5.3.1 Data . 181 5.3.2 Further data cleaning . 184 5.3.3 Statistical Analyses . 184 5.3.4 Sensitivity analyses . 186 5.4 Results . 186 5.4.1 Data cleaning and descriptive statistics . 186 5.4.2 Age standardised incident hospitalisation rates . 187 5.4.3 Indices of inequality . 205 5.4.4 Fractional Polynomials . 209 5.4.5 Multilevel Modelling . 214 5.4.6 Sensitivity analyses . 219 5.5 Discussion . 227 5.5.1 Principal findings . 227 5.5.2 Strengths and limitations . 229 5.5.3 Relations to other studies . 230 Table of Contents 7 5.5.4 Implications . 231 5.5.5 Next steps . 232 6 Amenable mortality by individual measures of socioeconomic position 233 6.1 Introduction . 233 6.2 Individual measures of Socioeconomic Position . 234 6.2.1 Educational Attainment . 234 6.2.2 Income . 240 6.2.3 Occupational Social Class . 242 6.2.4 Composition and relationships within households . 246 6.2.5 Ethnicity and Race . 250 6.2.6 Place of residence . 252 6.2.7 Conclusions . 254 6.3 Objectives . 255 6.4 Methods . 255 6.4.1 Data source . 255 6.4.2 Study exposures and covariates . 257 6.4.3 Study Outcome . 263 6.4.4 Person years at risk . 263 6.4.5 Statistical Analyses . ..