Trwałość pierwszych związków w kohortach urodzeniowych 1951-1960 oraz 1961-1970

A family, as the basic social unit has been a subject to statisticians’ and demographists’ research for many years. Recently, the marriage institution has changed not only regarding the age at which people marry and the number of children they have but also in terms of its stability. At the same time, alternative forms of family appeared, mostly cohabitations. Such a variety complicates analysis of functioning and stability of a family. It becomes even more complicated regarding the fact that cohabitation often precedes marriage thus it needs to be decided whether it should be analyzed independently or rather in relation to the marriage that comes next. However, increasing divorce rate as well as cohabitations which are more common lead to the question on the stability of marriages and informal relationships as well as other changes observed recently in this area. The main objective of the study is to analyze and compare the stability of first relationships for women from birth cohorts 1951–1960 and 1961–1970. Cohort analysis makes it possible to present the changes in marital stability that have been observed for women from demographic decline cohort (1961–1970) as compared to women from demographic bulge cohort (1951–1960). Analyzed data comes from the questionnaire D (Fertility in Poland) of the National Population and Housing Census 2002

Low Hydrophobic Mismatch Scores Calculated for HLA-A/B/DR/DQ Loci Improve Kidney Allograft Survival

We evaluated the impact of human leukocyte antigen (HLA) disparity (immunogenicity; IM) on long-term kidney allograft survival. The IM was quantified based on physicochemical properties of the polymorphic linear donor/recipient HLA amino acids (the Cambridge algorithm) as a hydrophobic, electrostatic, amino acid mismatch scores (HMS\AMS\EMS) or eplet mismatch (EpMM) load. High-resolution HLA-A/B/DRB1/DQB1 types were imputed to calculate HMS for primary/re-transplant recipients of deceased donor transplants. The multiple Cox regression showed the association of HMS with graft survival and other confounders. The HMS integer 0-10 scale showed the most survival benefit between HMS 0 and 3. The Kaplan-Meier analysis showed that: the HMS=0 group had 18.1-year median graft survival, a 5-year benefit over HMS\u3e0 group; HMS ≤ 3.0 had 16.7-year graft survival, a 3.8-year better than HMS\u3e3.0 group; and, HMS ≤ 7.8 had 14.3-year grafts survival, a 1.8-year improvement over HMS\u3e7.8 group. Stratification based on EMS, AMS or EpMM produced similar results. Additionally, the importance of HLA-DR with/without -DQ IM for graft survival was shown. In our simulation of 1,000 random donor/recipient pairs, 75% with HMS\u3e3.0 were re-matched into HMS ≤ 3.0 and the remaining 25% into HMS≥7.8: after re-matching, the 13.5 years graft survival would increase to 16.3 years. This approach matches donors to recipients with low/medium IM donors thus preventing transplants with high IM donors

Extensions of cox model for non-proportional hazards purpose

Cox proportional hazard model is one of the most common methods used in time to event analysis. The idea of the model is to define a hazard level as a dependent variable which is explained by the time-related component (so-called baseline hazard) and the covariates- related component. The model is based on several restrictive assumptions one of which is the assumption of proportional hazard. However, if this assumption is violated, this does not necessarily prevent an analyst from using Cox model. The current paper presents two ways of model modification in the case of non-proportional hazards: introducing interactions of selected covariates with function of time and stratification model. Calculations performed give the evidence that both methods result in better model fit as compared with the original model. Additionally, they allow interpreting the parameters estimates more precisely, taking into account the effect of the covariate at the hazard level that is changing over time. The choice of the appropriate method of tied events handling however is not straightforward and should be adjusted to the particular analysis purpose

Ability of first relationships for women from birth cohorts 1951–1960 and 1961–1970

A family, as the basic social unit has been a subject to statisticians' and demographists' research for many years. Recently, the marriage institution has changed not only regarding the age at which people marry and the number of children they have but also as concerns its stability. At the same time, alternative forms of family appeared, mostly cohabitations. Such a variety complicates analysis of functioning and stability of a family. It becomes even more complicated regarding the fact that cohabitation often precedes marriage thus it needs to be decided whether it should be analyzed independently or rather in relation to the marriage that comes next. However, increasing divorce rate as well as cohabitations which are more common lead to the question on the stability of marriages and informal relationships as well as other changes observed recently in this area. The main objective of the study is to analyze and compare the stability of first relationships for women from birth cohorts 1951-1960 and 1961-1970.Cohort analysis makes it possible to present the changes in marital stability that have been observed for women from demographic decline cohort (1961-1970) as compared to women from demographic bulge cohort (1951-1960). Analyzed data comes from the questionnaire D (Fertility in Poland) of the National Population and Housing Census 2002