Searching for longevity determinants:

Sommaire

1 Introduction ..............................................................................................1
1.1 Longevity studies in Sardinia..................................................................................2
1.2 Aim, objectives and study design............................................................................5
1.3 Thesis organization .................................................................................................6
2 The secret of longevity: Genes, Fountain of Youth or Shangri-la?.....9
2.1 The possible determinants of longevity ..................................................................9
2.1.1 Sex..................................................................................................................12
2.1.2 Familial transmission of longevity................................................................14
2.1.3 Early-life conditions.......................................................................................22
2.1.4 Other pieces of the puzzle ..............................................................................26
2.2 An integrated model for the study of longevity ...................................................30
2.3 Conclusion.............................................................................................................32
3 The municipality of Villagrande Strisaili: from past to present .......35
3.1 The population of Villagrande Strisaili: from past to present ...............................35
3.2 General demographic trends..................................................................................40
3.3 Socio-economic conditions ...................................................................................44
3.4 Life trajectories of newborns in Villagrande Strisaili (1866-1915) ......................49
3.5 Conclusion.............................................................................................................52
4 Data: collection, sources, and quality...................................................55
4.1 Data collection.......................................................................................................55
4.2 Data sources ..........................................................................................................57
4.3 Data Quality ..........................................................................................................61
4.4 Conclusion.............................................................................................................64
5 The VI-llagrande L-ongevity D-atabase (VILD).................................65
5.1 Family reconstructed databases: review and strong points ...................................65
5.2 The creation of the VI-llagrande L-ongevity D-atabase (VILD) ..........................67
5.2.1 Selection of VILD newborns..........................................................................67
5.2.2. The issue of "non-local" newborns: implications of exclusion.....................71
5.2.3 Individual linkage procedure and final coverage of known survival for VILD
newborns .................................................................................................................74
5.2.4 Handling partial information: censoring strategy in the VILD......................77
5.2.5 Complete cases and partial information: implications on the analysis ..........81
5.3 The fifty-year old VILD newborns group .............................................................83
5.4 Conclusion.............................................................................................................85
6 Methods ...................................................................................................87
6.1 Definition of event, state space and censoring......................................................87
6.2 Survival analysis methods.....................................................................................88
6.3 The Cox proportional hazard model......................................................................90
6.4 The VILD Cox proportional hazard model ...........................................................93
6.5 Conclusion.............................................................................................................94
7 Empirical Model .....................................................................................95
7.1 The process leading to the empirical model..........................................................95
7.2 The coding procedure............................................................................................96
7.3 The operationalisation of variables .......................................................................98
7.3.1 Gender ..........................................................................................................103
7.3.2 Familial transmission of longevity...............................................................103
7.3.3 Environmental conditions ............................................................................109
7.4 Conclusion...........................................................................................................110
8 Mortality trajectories among the VILD newborns ...........................113
8.1 Infant and child mortality....................................................................................113
8.2 Mortality from 5 to 18 years old .........................................................................119
8.3 Young adult mortality: the role of maternal mortality and accidental deaths .....121
8.4 From 50 years old to oldest-old mortality...........................................................124
8.5 Life expectancy: estimation and comparison ......................................................126
8.6 Conclusion...........................................................................................................130
9 Searching for longevity determinants ................................................133
9.1 Differential survival among defined groups of fifty-year-old and over VILD
newborns ...................................................................................................................133
9.2 Identification of possible individual determinants of longevity..........................146
9.3 Conclusion...........................................................................................................158
10 Conclusions .........................................................................................161
References ................................................................................................165