We retrospectively evaluated the medical records of Caucasian patients referred to the Auxoendocrinology and Paediatric Gynaecology Unit of the Meyer Children’s University Hospital for CPP (group 1) during and after the Italian lockdown for the COVID-19 infection (March – July 2020), comparing this data with the medical records of the same period of the previous 5 years (March–July 2015–2019) (control group 1). We also collected data on the rate of pubertal progression (the tempo of puberty) in patients already followed by our Unit for untreated and slow progressive PP (group 2), again comparing the data with the same period of the previous 5 years (control group 2).
Patients with a diagnosis of CPP and associated hypothalamic–pituitary congenital malformations, neurological, neurosurgical and/or genetic diseases, psychomotor delay, oncological diseases, other endocrine impairments requiring hormonal treatments, or taking drugs that may interfere with pubertal development were excluded from the study. We also excluded children who were adopted or had immigrated to Italy as such children have a statistically higher rate of precocious puberty than the general pediatric population.
The study was performed according to the Helsinki II declaration and approved by the local Paediatric Ethical Committee (approval number: 30/07/2020–179). Written informed consent was obtained from the parents of enrolled children.
All patients underwent a physical examination and auxological evaluation. We recorded height, weight, body mass index (BMI), height velocity (HV) and stage and rate of pubertal progression (Tanner scale) . HV was calculated at least once in every year and was defined as the increase in height in centimeters per year . BMI was calculated by dividing the patient’s weight in kilograms by the square of height in meters . Height, HV and BMI were normalized for chronological age by conversion to SD scores . When possible, target height (TH) SD scores were also calculated.
If available, we collected clinical data (e.g. age at CPP diagnosis, personal and family history for major diseases, family history for CPP) and endocrinological data (follicle-stimulating hormone [FSH], luteinizing hormone [LH], estradiol [E2], dehydroepiandrosterone sulfate [DHEAS], 17-hydroxyprogesterone [17-OHP], prolactin [PRL], free thyroxine [FT4], thyroid-stimulating hormone [TSH]). In addition, a pelvic ultrasonography, a bone age (BA) assessment using radiographs of the left hand and wrist and a LH-releasing hormone (LHRH) stimulation test were performed.
Pubertal development was classified according to the Marshall and Tanner criteria . The age of pubertal onset was defined as the age at durable Tanner B2 stage, confirmed by the auxological, endocrinological and/or radiological results . The rate of pubertal progression was taken to be the time from B2 to B3 and/or B4 .
Skeletal maturation was expressed as BA and evaluated, when possible, as the ratio of the change in BA to the change in chronological age (CA) (BA/CA), and as the difference between CA and BA (CA minus BA) in years .
Precocious puberty was defined as the development of pubertal changes at an age that was younger than the accepted lower limits for age of onset of puberty (before the age of 8 years in girls) . We considered peak LH values of > 5 IU/L on the GnRH in the presence of pubertal signs or a basal LH value of > 1.1 IU/L and a ratio of stimulated LH to stimulated FSH of > 1.0 combined with isolated and/or axillary hair growth accompanied by breast development  to be indicative of activation of the hypothalamic GnRH pulse generator.
For the purposes of this study, the rate of puberty progression was evaluated:
for group 1 patients with new CPP diagnoses and control group 1, by the time between the appearance of a durable Tanner stage 2 and diagnosis. For these patients auxological parameters were recorded at diagnosis and compared with those recorded by the patient’s paediatrician at the moment of referral.
for group 2 patients with untreated CPP patients who had presented slow progression prior to lockdown and control group 2, by the progression rate assessed by a Paediatric Endocrinologist (S.S.). All CPP patients are assessed every 3–4 months by our Unit to determine whether the rate of pubertal progression is stable or accelerating. We defined slow or accelerated pubertal development if the rate of progression from one pubertal stage to another is more or less than 6 months or 1 SD in comparison with the general population [19, 20].
Moreover, based on our previous data , we also evaluated quantitatively and qualitatively changes in the use of electronic devices before and during lockdown in these patients . Parents were asked to complete a questionnaire specifying which devices children used, how long they used them for, at what times of the day and whether they were used by the children in their bedrooms during the hours before they went to sleep. The devices considered were: PCs, cell phones, MP3 players, tablets, game consoles and TVs. Data were collected after the lockdown. Time spent on screen-based activity was assessed by the following question: “including school hours (only during lockdown), how much time do you (the child) usually spend on the following: (1) TV, (2) TV-games (PlayStation, Xbox, WII, etc), (3) PC games, (4) Internet chatting, (5) using the PC for other purposes)?” The response alternatives were: ‘no time’, ‘less than ½ hour’, ‘½ hour to 1 hour’, 1 h to 2 h’, ‘2 hours to 3 hours’, ‘3 hours to 4 hours’, ‘4 hours to 5 hours’ and ‘more than 5 hours’. Most recommendations for screen-based activities restrict screen time for children and adolescents to about 2 h per day .
Height was measured using Harpenden’s stadiometer in triplicate to the nearest 0.1 cm. Weight was determined to the nearest 0.1 kg using a balance scale. Age-related reference values for height, bone age and BMI were those currently used in Italy, obtained in high sample numbers of Italian children, as previously reported [14, 15]. Height, HV, and BMI were normalized for chronological age by conversion to standard deviation (SD) scores according to the following formula: patient value – mean of age-related reference value/standard deviation of the age-related reference value [14, 15]. BA was evaluated through radiographs of the left hand and wrist and then calculated according to the Greulich and Pyle method . TH was estimated according to the Hermanussen and Cole method , calculating mid-parent height as an SD score and correcting this by a factor corresponding to the influence of assortative mating and parent-offspring correlations.
Pelvic ultrasonography was performed by the same operator (E.B.), using a Siemens Sonoline Elegra sonograph and a 6.5-MHz probe. The surface area (S) of the ovaries was calculated as follows: S = length x width × 0.8. The normal ovarian surface area is < 2 cm2 in prepubertal and from 2 to 6 cm2 in pubertal subjects .
All laboratory measurements were performed on blood samples collected after overnight fasting. Plasma FSH and LH, PRL, 17OHP, DHEAS, FT4, TSH, and E2 levels were measured by means of chemiluminescent immunometric assays with the use of commercially available kits for the Immulite 2000 systems analyzer (Siemens Healthcare Diagnostics).
The LHRH test was carried out by taking blood samples at the 15th, 30th, 45th and 60th minute after intravenous administration of 100 mg/m2 (maximum 100 mg) LHRH (Lutrelef, 0.8 mg/10 mL; Ferring).
Statistical analyses were performed with the use of SPSS X software (SPSSX Inc., Chicago, IL, USA). The characteristics of the study population were described using frequency distributions for categorical variables and mean and standard deviation (SD) values, medians, and ranges for continuous variables, depending on whether the data were normally distributed. The statistical significance of the continuous variable comparisons was assessed using the Student t test and the Mann-Whitney U test, depending on the distribution of the analyzed variable; the comparison of categorical variables was conducted using the chi square test or Fisher’s Exact test if there was a small (< 5) expected cell size. The Pearson correlation test was used to determine the correlation coefficients. All statistical tests were two-tailed and a p < 0.05 was considered statistically significant.