The LIFE Child study is a large population-based longitudinal childhood cohort study conducted in the city of Leipzig, Germany. As a part of LIFE, a research project conducted at the Leipzig Research Center for Civilization Diseases, it aims to monitor healthy child development from birth to adulthood and to understand the development of lifestyle diseases such as obesity. The study consists of three interrelated cohorts; the birth cohort, the health cohort, and the obesity cohort. Depending on age and cohort, the comprehensive study program comprises different medical, psychological, and sociodemographic assessments as well as the collection of biological samples. Optimal data acquisition, process management, and data analysis are guaranteed by a professional team of physicians, certified study assistants, quality managers, scientists and statisticians. Due to the high popularity of the study, more than 3000 children have already participated until the end of 2015, and two-thirds of them participate continuously. The large quantity of acquired data allows LIFE Child to gain profound knowledge on the development of children growing up in the twenty-first century. This article reports the number of available and analyzable data and demonstrates the high relevance and potential of the study.

BackgroundProfound knowledge about child growth, development, health, and disease in contemporary children and adolescents is still rare. Epidemiological studies together with new powerful research technologies present exciting opportunities to the elucidation of risk factor-outcome associations with potentially major consequences for prevention, diagnosis and treatment.AimTo conduct a unique prospective longitudinal cohort study in order to assess how environmental, metabolic and genetic factors affect growth, development and health from fetal life to adulthood.MethodsThe ‘Leipzig Research Centre for Civilization Diseases (LIFE) Child Study’ focuses on two main research objectives: (1) monitoring of normal growth, development and health; (2) non-communicable diseases such as childhood obesity and its co-morbidities, atopy and mental health problems. Detailed assessments will be conducted alongside long-term storage of biological samples in 2,000 pregnant women and more than 10,000 children and their families.ResultsClose coordination and engagement of a multidisciplinary team in the LIFE Child study successfully established procedures and systems for balancing many competing study and ethical needs. Full participant recruitment and complete data collection started in July 2011. Early data indicate a high acceptance rate of the study program, successful recruitment strategies and the establishment of a representative cohort for the population of Leipzig. A series of subprojects are ongoing, and analyses and publications are on their way.DiscussionThis paper addresses key elements in the design and implementation of the new prospective longitudinal cohort study LIFE Child. Given the recognized need for long-term data on adverse effects on health and protective factors, our study data collection should provide magnificent opportunities to examine complex interactions that govern the emergence of non-communicable diseases.

The aim of the present study was to evaluate oral health-related quality of life (OHRQoL) impairment in patients seeking care for their hypersensitive teeth in comparison with general population subjects and to investigate the influence of gender and age on OHRQoL in these populations. Study participants were 656 patients without removable prosthodontics who sought treatment for their hypersensitive teeth in German dental offices. These patients were asked to complete the German form of the Oral Health Impact Profile (OHIP-G) prior to treatment. The sum of OHIP-G item responses (OHIP-G49, 0-196) characterized the OHRQoL impairment. Patients' OHIP summary scores were compared with those in a sample of the German general population (n = 1541). The influence of population (patients vs. general population subjects), gender and age was investigated using a multivariable linear regression model. Age presented a curvilinear association with OHRQoL, with lower OHIP scores associated with younger and older adults and higher OHIP scores (indicating impaired OHRQoL) associated with middle-aged adults in both the patient and general populations. Gender influence depended on the population, i.e. female general population subjects had lower OHIP scores than male general population subjects and female patients had higher OHIP scores than male patients. Mean OHIP summary scores indicated that patients with hypersensitive teeth reported considerably more impaired OHRQoL (approximately 22 OHIP units) than subjects in the general population. The present study suggests that the oral condition of hypersensitive teeth is significantly associated with impaired OHRQoL.

The aims of this study were, first, to report normative values for jaw movements in Caucasian children and adolescents (maximum opening, laterotrusion, and protrusion) and, second, to investigate the influence of age, gender, and temporomandibular disorders (TMD) on jaw movement capacity. The population-based study included 1,011 randomly selected German children and adolescents, aged 10-17 yr. Case histories, as well as mandibular movements and the presence of TMD, were assessed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The mean +/- standard deviation for maximum opening was 50.6 +/- 6.4 mm, for laterotrusion to the right was 10.2 +/- 2.2 mm, for laterotrusion to the left was 10.6 +/- 2.3 mm, and for protrusion was 8.2 +/- 2.5 mm. Bivariable (t-test) and multivariable (linear regression) analyses showed that normative values for jaw opening capacity were influenced by age and gender. No influence on jaw movement capacity was seen when TMD were present. Based on the distribution of the measurements in the population (lowest decentile), the mandibular mobility of subjects with a maximum opening of < 43 mm and laterotrusive movements < 8 mm or protrusive movements < 5 mm might be considered as being limited. However, these limitations do not necessarily require treatment.

The aim of this study was to analyze whether generalized joint hypermobility (GJH) is a risk factor for temporomandibular disorders (TMD). We examined 895 subjects (20-60 yr of age) in a population-based cross-sectional sample in Germany for GJH according to the Beighton classification and for TMD according to the Research Diagnostic Criteria for TMD (RDC/TMD). After controlling for the effects of age, gender, and general joint diseases using multiple logistic regression analyses, hypermobile subjects (with four or more hypermobile joints on the 0-9 scale) had a higher risk for reproducible reciprocal clicking as an indicator for disk displacement with reduction (Odds Ratio (OR) = 1.68) compared with those subjects without hypermobile joints. Concurrently, subjects with four or more hypermobile joints had a lower risk for limited mouth opening (< 35 mm; OR = 0.26). The associations between GJH and reproducible reciprocal clicking or limited mouth opening were statistically significant in a trend test. No association was observed between hypermobility and myalgia/arthralgia (RDC/TMD Group I/IIIa). In conclusion, GJH was found to be associated with non-painful subtypes of TMD.

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The aims of this study were to develop a German version of the Child Perceptions Questionnaire (CPQ11-14, a measure of oral health-related quality of life in 11-14-year-old children) and to assess the instrument's reliability and validity in German children ages 11-14. The English original version of the CPQ11-14 questionnaire was translated into German (CPQ-G11-14) by a forward-backward translation method. Reliability was investigated in 1,061 subjects aged 11-14 years from a regional sample (Wernigerode, Saxonia-Anhalt, Germany) who were recruited during the annual dental public health examination. The subjects completed the CPQ-G11-14 and were clinically examined for the presence of dental caries, plaque accumulation, and malocclusion. In the reliability assessment, questionnaire summary score test-retest reliability was excellent (intraclass correlation coefficient, 95% confidence interval (CI) = 0.83, 0.73-0.94) and internal consistency was satisfactory (Cronbach's alpha, lower limit of CI = 0.87, 0.86). Validity of the CPQ-G11-14 questionnaire was supported by correlations with global ratings of oral health and overall well-being that were moderate in magnitude and met expectations (r = 0.35; 95% CI, 0.30-0.40 and r = 0.30; 95% CI, 0.24-0.35, respectively). In conclusion, the German version of the CPQ11-14 was reliable and valid in a general population of 11-14-year-old German children.

Pubertal development increases the probability of self-reported TMD symptoms among girls, while the probability thereof decreases among boys. Independent of sex, pubertal growth increases the prevalence of RDC/TMD-related diagnoses-mainly disk displacement-in both sexes.