André Hajek

Prof. Dr. André Hajek

Department of Health Economics and Health Services Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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JHJohanna Katharina Hohls
Johanna Katharina Hohls
HKHans-Helmut König
Hans-Helmut König
EQEleanor Quirke
Eleanor Quirke
AHAndré Hajek
André Hajek
This review aimed to systematically review observational studies investigating the longitudinal association between anxiety, depression and quality of life (QoL). A systematic search of five electronic databases (PubMed, PsycINFO, PSYNDEX, NHS EED and EconLit) as well as forward/backward reference searches were conducted to identify observational studies on the longitudinal association between anxiety, depression and QoL. Studies were synthesized narratively. Additionally, a random-effects meta-analysis was performed using studies applying the mental and physical summary scores (MCS, PCS) of the Short Form Health Survey. The review was prospectively registered with PROSPERO and a study protocol was published. n = 47 studies on heterogeneous research questions were included, with sample sizes ranging from n = 28 to 43,093. Narrative synthesis indicated that QoL was reduced before disorder onset, dropped further during the disorder and improved with remission. Before onset and after remission, QoL was lower in comparison to healthy comparisons. n = 8 studies were included in random-effects meta-analyses. The pooled estimates of QoL at follow-up (FU) were of small to large effect sizes and showed that QoL at FU differed by disorder status at baseline as well as by disorder course over time. Disorder course groups differed in their MCS scores at baseline. Effect sizes were generally larger for MCS relative to PCS. The results highlight the relevance of preventive measures and treatment. Future research should consider individual QoL domains, individual anxiety/depressive disorders as well as the course of both over time to allow more differentiated statements in a meta-analysis.

21 September 2017 in Age and Ageing
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AHAndré Hajek
André Hajek
JBJens-Oliver Bock
Jens-Oliver Bock
KSKai-Uwe Saum
Kai-Uwe Saum
HMHerbert Matschinger
Herbert Matschinger
HBHermann Brenner
Hermann Brenner
HKHans-Helmut König
Hans-Helmut König
To investigate how frailty and frailty symptoms affect healthcare costs in older age longitudinally. data were gathered from a prospective cohort study in Saarland, Germany (two waves with 3-year interval, n = 1,636 aged 57–84 years at baseline). Frailty was assessed by the five Fried frailty criteria. Frailty was defined as having at least three criteria, the presence of 1–2 criteria as ‘pre-frail’. Healthcare costs were quantified based on self-reported healthcare use in the sectors of inpatient treatment, outpatient treatment, professional nursing care and informal care as well as the provision of pharmaceuticals, medical supplies and dental prostheses. while the onset of pre-frailty did not increase (log) total healthcare costs after adjusting for potential confounders including comorbidity, progression from non-frailty to frailty was associated with an increase in total healthcare costs (for example, costs increased by ~54 and 101% if 3 and 4 or 5 symptoms were present, respectively). This association of frailty onset with increased healthcare costs was in particular observed in the inpatient sector and for informal nursing care. Among the frailty symptoms, the onset of exhaustion was associated with an increase in total healthcare costs, whereas changes in slowness, weakness, weight loss and low-physical activity were not significantly associated with an increase in total healthcare costs. our data stress the economic relevance of frailty in late life. Postponing or reducing frailty might be fruitful in order to reduce healthcare costs.

14 December 2015 in PLOS ONE
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AHAndré Hajek
André Hajek
CBChristian Brettschneider
Christian Brettschneider
CLCarolin Lange
Carolin Lange
TPTina Posselt
Tina Posselt
BWBirgitt Wiese
Birgitt Wiese
AGAgeCoDe Study Group
AgeCoDe Study Group
To investigate time-dependent predictors of institutionalization in old age using a longitudinal approach. In a representative survey of the German general population aged 75 years and older predictors of institutionalization were observed every 1.5 years over six waves. Conditional fixed-effects logistic regressions (with 201 individuals and 960 observations) were performed to estimate the effects of marital status, depression, dementia, and physical impairments (mobility, hearing and visual impairments) on the risk of admission to old-age home or nursing home. By exploiting the longitudinal data structure using panel econometric models, we were able to control for unobserved heterogeneity such as genetic predisposition and personality traits. The probability of institutionalization increased significantly with occurrence of widowhood, depression, dementia, as well as walking and hearing impairments. In particular, the occurrence of widowhood (OR = 78.3), dementia (OR = 154.1) and substantial mobility impairment (OR = 36.7) were strongly associated with institutionalization. Findings underline the strong influence of loss of spouse as well as dementia on institutionalization. This is relevant as the number of old people (a) living alone and (b) suffering from dementia is expected to increase rapidly in the next decades. Consequently, it is supposed that the demand for institutionalization among the elderly will increase considerably. Practitioners as well as policy makers should be aware of these upcoming challenges.

AHAndré Hajek
André Hajek
BKBenedikt Kretzler
Benedikt Kretzler
HKHans-Helmut König
Hans-Helmut König
Background: Several empirical studies have shown an association between informal caregiving for adults and loneliness or social isolation. Nevertheless, a systematic review is lacking synthesizing studies which have investigated these aforementioned associations. Therefore, our purpose was to give an overview of the existing evidence from observational studies. Materials and Methods: Three electronic databases (Medline, PsycINFO, CINAHL) were searched in June 2021. Observational studies investigating the association between informal caregiving for adults and loneliness or social isolation were included. In contrast, studies examining grandchild care or private care for chronically ill children were excluded. Data extractions covered study design, assessment of informal caregiving, loneliness and social isolation, the characteristics of the sample, the analytical approach and key findings. Study quality was assessed based on the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Each step (study selection, data extraction and evaluation of study quality) was conducted by two reviewers. Results: In sum, twelve studies were included in our review (seven cross-sectional studies and five longitudinal studies)—all included studies were either from North America or Europe. The studies mainly showed an association between providing informal care and higher loneliness levels. The overall study quality was fair to good. Conclusion: Our systematic review mainly identified associations between providing informal care and higher loneliness levels. This is of great importance in assisting informal caregivers in avoiding loneliness, since it is associated with subsequent morbidity and mortality. Moreover, high loneliness levels of informal caregivers may have adverse consequences for informal care recipients.

1 May 2020 in Archives of Gerontology and Geriatrics
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NPNicola Petersen
Nicola Petersen
HKHans-Helmut König
Hans-Helmut König
AHAndré Hajek
André Hajek

11 July 2022 in Social Psychiatry and Psychiatric Epidemiology
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BKBenedikt Kretzler
Benedikt Kretzler
HKHans-Helmut König
Hans-Helmut König
AHAndré Hajek
André Hajek
Purpose: Several publications explored a relationship between pet ownership and lower levels of loneliness and social isolation. However, to the best of our knowledge, no systematic review has yet synthesized the evidence on these associations. Thus, this systematic review aims to evaluate the findings regarding the relations between pet ownership, loneliness, and social isolation. Methods: PubMed, CINAHL, and PsycInfo were searched in January 2022. Observational studies relying on appropriate instruments to assess the exposure and the outcome variables were included. Two reviewers independently executed study selection, data extraction, and quality assessment. Results: n = 24 studies were included. Among adult samples, the studies examining the relationship between pet ownership and social isolation found that owning a pet was associated with lower levels of social isolation. Concerning loneliness, studies that were conducted after the outbreak of COVID-19 mostly showed that pet ownership can contribute to lower levels of loneliness, but did not reveal an overall significant association until then. In turn, the studies that examined child and adolescent samples suggest that pet ownership was related to reduced loneliness before COVID-19. Furthermore, most of the studies did not reveal any differences between dogs, cats, and other kinds of pets regarding their relationship to loneliness and social isolation. Conclusion: All in all, only a part of the studies detected a significant association between pet ownership, loneliness and social isolation. However, the COVID-19 pandemic seemed to strengthen this relationship, so that future research is required to assess the longevity of this potential effect.