Design and setting
This study is a prospective observational study. It included all consecutive patients admitted to The Children’s Obesity Clinic, Department of Paediatrics, Nordsjællands Hospital, Hillerød, from February 2010 to March 2013.
Patients between 5 and 18 years with a BMI above the 99th percentile for sex and age according to the Danish BMI charts  or a BMI rise of more than 5 percentiles in less than 2 years were eligible for referral. No exclusion criteria were used and patients could remain in treatment until the age of 18 or longer if it was deemed necessary. Patients were referred from their general practitioners, school- and community- based doctors, the Department of Pediatrics, Nordsjællands Hospital, or from other pediatric departments in the Capital Region of Denmark.
The first visit in the clinic (baseline investigation, 1 hour) was performed by a pediatrician to identify obesity and to screen for underlying causes and possible complications. At baseline, the following variables were obtained: Height was measured by Seca 216 stadiometer, to the nearest millimeter, calibrated monthly by use of a standard-100 cm measure. Weight was measured on a standard calibrated Tanita BC-418 MA to the nearest 0.1 kg without shoes and in light indoor clothing, without need for calibration before 300.000 measurements . Pubertal stage was rated according to Tanner stages. Girls were asked if menarche had occurred. Testicular size was measured by Prader’s orchidometer.
A detailed lifestyle history was provided by the patient and his/her parents in an interview by the pediatrician. The lifestyle history included eating behavior, dietary habits, exercise, transportation patterns, inactivity, bullying, social life, the family’s socioeconomic status, ethnicity, and family structure. Parents BMI was calculated based on self-reported height and weight. Parents were classified as having a normal weight (BMI < 25), being overweight (25 > BMI < 30), or being obese (BMI > 30) according to WHO guidelines . Family structure was classified as follows, by whom the patient was living with: (a) both parents, (b) disrupted family (i.e. single or divorced parents with or without stepfamily), or (c) alternative family structures such as foster families, group homes, or with other family members. The investigation and interview form is available from the authors.
Socioeconomic status (SES) was defined in groups of 1–5 based on the National Statistics Socio-economic Classification . The groups were divided according to occupation as follows: 1. Self-employed, chief executive directors, employees whose work requires skills of the highest educational level. 2. Employees whose work requires skills of a medium long educational level. 3. Trained workers and employees whose work requires skills of a short educational level. 4. Untrained workers, temporary unemployed, and students. 5. People outside the workforce (e.g. senior citizens and disability pensioners). Groups were re-categorised into 1–2: high SES and 3–5: low-medium SES.
To ensure reliable data collection, the clinic’s staff members received one-day training in the use of the TCOCT protocol during a study visit at The Children’s Obesity Clinic, Department of Pediatrics, Holbæk University Hospital. Thereafter, all nurses, dieticians, and pediatricians starting in the clinic received training and supervision from more experienced colleagues.
A trusting relationship between the family and the health care personnel was sought established through a structured pedagogical conversation. This strategy sought to optimise diagnosis, treatment, and follow-up of patients and to provide the patient and his/her family with a set of tools in order to implement the needed lifestyle changes. The pediatrician defined a structured and individually tailored treatment plan for the patient in collaboration with the family. The treatment plan was based on the lifestyle history as well as the patient and his/her family’s daily routines such as school and work hours, place of residence, and spare time activities. Any additional underlying disease to obesity, e.g. Prader-Willi syndrome, was integrated in the treatment plan. The plan was delivered in hard copy to support the necessary lifestyle and behavioral changes and to help the patient and his/her family to control the environment. The treatment plan structure offers potentially more than ninety items of advices , but individual treatment plans typically contained 15–20 advices at the baseline visit. After the follow-up visits (see below), patients were seen annually by a pediatrician (30 min) to monitor the treatment response and address any necessary adjustments in the treatment plan.
Follow-up visits (45 min) with a trained pediatric nurse were offered in intervals of 8–10 weeks. The follow-up intervals were individualised to the family’s needs and resources (i.e. depending on the patient’s treatment progression, and on practical limitations). Patients were followed by the same nurse to maintain a secure environment for the patient. Regardless of treatment response, families were supported when they showed up at appointments and were reinforced on advices that were integrated in their daily lives. Lack of adherence to intervention advices were specifically identified and discussed and re-implemented, so the treatment plan was revised accordingly. In treatment, all patients were offered one visit (45 min) with a dietician. The dietician would monitor the treatment progression and further specify or modify the diet for the patient. If the family lacked considerable knowledge regarding dieting, food, and cooking, the dietician would offer a second consultation (45 min). Height and weight were measured at all visits by nurses, dieticians, or pediatricians.
Patients were discharged if they missed more than three scheduled appointments and were then categorised as dropouts. Clinical success and hence discharge were decided by the pediatrician using the following criteria: If the patient and the family’s understanding and adherence of the treatment plan were satisfactory and if the patient’s BMI had decreased or stabilised, success was ascertained. The patients were followed until clinical success was achieved, the patients dropped out, the patients moved away, or the patients reached their 25th birthday.
All measurements were entered into a Microsoft Access database and exported to Statistical Analysis Software (SAS) for the analyses. Body mass index standard deviation scores (BMI SDS) were determined based on the distribution of a Danish population with the same sex and age , using the LMS method. BMI of parents was calculated as weight divided by height squared. The levels of baseline BMI SDS in different groups of patients were compared using ANOVA. The longitudinal development of BMI SDS during treatment was modeled using a generalised linear mixed model. The covariance structure includes a random intercept, allowing each child to have his/her own overall level of BMI SDS, and an exponential residual structure, allowing the covariance between two measurements on the same child to decrease as the time between measurements increases. The mean value of BMI SDS was modeled as a function of time since initiation of treatment, using a cubic spline with three a priori -chosen knots (at 2, 11, and 33 months, respectively). The associations between change in obesity and baseline characteristics were assessed by performing a test for interaction between a dichotomised version of the baseline characteristic and time since treatment initiation in the generalised linear mixed model. The degree of retention was illustrated by a Kaplan-Meier plot and by calculating the equivalent retention rates after one and two years. Associations between baseline characteristics and retention were analysed with a cox regression analysis. P-values below 0.05 were considered statistically significant.
This study has been approved by the Danish Data Protection Agency; journal number: 2007-58-0015. All participants gave written consent to participate in treatment. The study is considered as a prospective observational quality development study. Therefore notification to the National Committee on Health Research Ethics or to the National Board of Health was not required [26,27]. All patients received state-funded treatment, as permanent residents in Denmark can use the Danish healthcare system free of charge.