[Excessive daytime sleepiness. An epidemiological study based on a "sleep/breathing" questionnaire]. / Somnolence diurne excessive. Étude épidémiologique basée sur un questionnaire « sommeil/respiration ¼

BACKGROUND: A field survey used a "sleep-breathing" questionnaire to estimate the prevalence of the excessive daytime sleepiness in a sample of middle-aged males. METHODS: Eight hundred and fifty men aged 22 to 66 years agreed to answer a questionnaire and have anthropometric measurements. To the question on excessive daytime sleepiness, 90 subjects (10.8%) responded "often" or "almost always"; 740 gave a negative answer. RESULTS: The sleepy subjects were older and had a higher "central" weight. All the sleep-disturbed breathing symptoms and those suggesting sleep disturbances were more frequent in sleepy subjects. Sleepiness was significantly associated with sleep apnea and chronic bronchitis. Logistic regression identified six items independently associated with daytime sleepiness; there were three indirect indicators of sleepiness, age, a history of chronic bronchitis and disruptive movements during sleep. CONCLUSIONS: This epidemiologic study in a sample of active middle-aged males confirms the association of daytime sleepiness with a series of respiratory and non-respiratory sleep disturbances. The original findings are the role of a "central" obesity, the association with nightmares, and the role of chronic bronchitis as a determinant of daytime sleepiness.

[Is a sedentary lifestyle a risk factor for sleep-related respiratory disturbance?]. / La sédentarité est-elle un facteur de risque de troubles respiratoires pendant le sommeil?

INTRODUCTION: This questionnaire-based epidemiological study was aimed at identifying possible sleep disturbance in a sample of active French males. METHODS: Eight hundred and fifty male subjects, aged 22 to 66 years, completed a structured sleep questionnaire supplemented by information about their life habits and medical history. The study compared the prevalence of positive responses between an "at risk" group of sedentary people (with no declared leisure exercise) and a control group of "exercising" subjects (with more than 5 hours of planned exercise weekly). RESULTS: Among the symptoms suggesting sleep-disordered breathing, only the question "Have you ever been told that you snore?" significantly separated the two groups. In addition, the sedentary group declared a history of treated hypertension significantly more often. CONCLUSIONS: The present survey identified only one item that differed significantly between a sedentary of men and an exercising group - a history of treated hypertension. The result may be explained by the limitations of a questionnaire survey and by the limited contrast in exercise practice: the "sedentary" subjects had an occupational labour demand (not quantified), and the control group had a relatively modest leisure physical activity.

Roles of age, length of service and job in work-related injury: a prospective study of 446 120 person-years in railway workers.

OBJECTIVES: Because work-related injuries are common and yet the mechanisms through which various types of injuries relate to age, length of service and job remain unknown, this study assessed the role of age, length of service and job in work-related injury. METHODS: Prospective study of all 164,814 permanently employed male workers at the French national railway company during 1998-2000, based on the company's injury database: 446,120 person-years, 15,195 injuries with working days lost, coded using the company's injury classification, which is derived from that of the French health insurance scheme. We investigated the incidence of 10 types of injury: fall on same level, fall to lower level, handling materials/machine parts during assembly, handling objects, lifting/handling equipment, collision with/by moving objects, collision with/by vehicles, operating machines/equipment, using hand tools and other injuries. Data were analysed using negative binomial regression. RESULTS: Workers aged <25 years were subject to a higher injury risk from handling materials/machine parts during assembly, and collision with/by moving objects or vehicles. Older workers, especially those aged 50-55 years, were subject to a higher risk of fall and injury resulting from lifting/handling materials/equipment/objects or from collision with/by moving objects/vehicles. Using hand tools was a risky task for workers aged <30 or > or =40 years. The relative risk decreased steadily with increasing length of service with the company, from 2.6 for 1 year to 1.0 for > or =30 years, and the slope of the trend is stronger for fall to lower level, lifting/handling materials/equipment and collision with/by moving objects. CONCLUSION: Younger and older ages and shorter length of service are at risk for various types of injuries. Preventive measures should improve working conditions, especially for younger/older ages, provide knowledge through specific training during the first years in a job and help workers to be more aware of risks associated with their age, years of employment and job.

Disnea de esfuerzo, deterioro del patrón ventilatorio y mala tolerancia al ejercicio: ¿ signos precoces de insuficiencia respiratoria? / Exertional dyspnea, rapid shallow breathing and poor exercise toleran Early signs of respiratory impairment?

IntroducciónLa disnea de esfuerzo (DE) es frecuente entre fumadores a pesar de una espirometría normal.ObjetivosDeterminar si el test de ejercicio y la observación de posibles alteraciones del patrón ventilatorio pueden reflejar una insuficiencia respiratoria precoz.Material y métodoSe ha comparado a 24 varones fumadores que presentaban DE con 31 varones fumadores sin DE. En ambos grupos se realizó espirometría, pletismografía, estudio del patrón ventilatorio, gasometría arterial y test de ejercicio incremental (30W/3min), empezando por 40W×10min. La se evaluó mediante la escala de Borg.ResultadosLa espirometría era normal en ambos grupos. Los sujetos con DE presentaron un aumento de la frecuencia respiratoria (fB) y un volumen corriente (VT) significativamente reducido (p<0,001), con un patrón respiratorio más superficial. Además, mostraban una reducción superior al 30% del consumo máximo del VÿO2pico y de la potencia máxima tolerada (Wmáx) (p<0,01). Se observó una disminución de la ventilación alveolar (VÿA/VÿE), la PaO2 y el pulso de O2 (p<0,01), mientras que la ventilación (VÿE), la relación ventilación (VE)/ventilación máxima minuto (MVV), el espacio muerto (VD), la lactatemia (AL) y la frecuencia cardiaca (FC) fueron, para un mismo nivel de ejercicio, significativamente mayores (p<0,01) en el grupo de disneicos.ConclusionesSujetos aparentemente sanos, cuya espirografía es normal, presentan DE, junto con una combinacion de efectos adversos durante el ejercicio (aumento de la demanda ventilatoria central, importantes alteraciones del patrón ventilatorio, con hipoventilación e importante reducción de la máxima cantidad de ejercicio). Tales alteraciones frecuentemente no se exploran, pero se podrían corregir mediante un elaborado tratamiento fisioterapéutico y entrenamiento muscular(AU)

AbstractExertional dyspnea (ED) is common among smokers despite a normal spirometry.ObjectivesThis study aimed to determine whether exercise testing, overbreathing and altered breathing pattern can reflect early respiratory impairment.Material and methodTwenty-four active ED male smokers aged 33–60 years, with no background of muscular, cardiac or respiratory disease, were compared to 31 healthy smokers (with no ED). Spirometry, plethysmography, ventilatory pattern and arterial blood gases were assessed in both groups and dyspnea was estimated using a Borg scale at every 30W/3min step of incremental maximal exercise, starting with 40W for 10min.ResultsSpirometry data was normal in both groups. Compared to healthy subjects, the respiratory pattern was significantly (p<0.001) more rapid and shallow with smaller tidal volume (VT) (p<0.001) and less alveolar ventilation (VÿA/VÿE) and PaO2 while ventilation (VÿE), the ratio VÿE/MVV, ventilatory frequency (fB), dead space ventilation (VD), lactic acidemia, and cardiac frequency (fC) were significantly higher (p<0.01) in the ED group. The significant differences (p<0.05) observed at rest were amplified during exercise and VÿO2 pico and maximal power load were 30% lower (p<0.001) in ED subjects.ConclusionsApparently healthy subjects, whose spirometry are normal, complain of exertional dyspnea associated with a combination of adverse effects of: increased central ventilatory demand, overbreathing, impairments of ventilatory pattern, hypoventilation, and severe reduction of the maximal levels of exercise. These changes are not often explored, although they are potentially susceptible to correction corrected with sophisticated respiratory physiotherapy and exercise training(AU)

Determinants of school injury proneness in adolescents: a prospective study.

OBJECTIVE: Injury proneness is common in adolescents, but the role of individual factors has received little attention. This study assessed the relationships of a number of individual characteristics with frequency of school injuries. METHODS: This prospective study was conducted on 2396 students from middle schools and high schools in an urban area in France over one school year. A questionnaire was completed by each student at the beginning of the school year, and an injury questionnaire was completed for all injuries that occurred at school during the year. Data were analysed using the chi2 independence test and logistic models. RESULTS: Over the study year, 10.6% of the students had a single injury. Frequent injuries (two or more) were common (2.3%) and were strongly related to younger age [adjusted odds ratio (aOR) 1.52, 95% confidence interval (95%CI) 1.28-1.79], frequent use of psychotropic drugs (aOR 2.03, 95%CI 1.06-3.86) and a poorer average school mark (<10/20, aOR 2.58, 95%CI 1.30-5.12). The occurrence of a single injury was less strongly related to younger age (aOR 1.20, 95%CI 1.11-1.30) and frequent use of psychotropic drugs (aOR 1.43, 95%CI 1.04-1.96), and was also associated with parental absence (aOR 1.33, 95%CI 1.00-1.77), not being calm (aOR 1.41, 95%CI 1.03-1.89) and not being easily irritated (aOR 1.56, 95%CI 1.14-2.13). CONCLUSIONS: This study identified a number of factors associated with injury frequency. This information could be useful for injury prevention. Physicians could help students, parents, teachers and school staff to be more aware of the risks and to find remedial measures.

[Occupational exposure to low concentrations of carbon monoxide and sleep disordered breathing. A negative result]. / Exposition à des faibles concentrations d'oxyde de carbone et troubles respiratoires pendant le sommeil. Un résultat négatif.

INTRODUCTION: This study explored the possibility that occupational exposure to low concentrations of carbon monoxide (CO) could influence the synchronisation of upper airway and lower respiratory muscles and thus induce sleep disordered breathing. METHODS: Two hundred and thirty subjects exposed to between 1 and 5 ppm (peaks up to 25 ppm) at work and one hundred and sixteen unexposed controls were studied with a protocol comprising anthropomorphic measurements and a self-completed French translation of the Wisconsin Sleep Questionnaire. RESULTS: The two groups had similar anthropomorphic and lifestyle data with the exception that the exposed group were slightly younger (2.5 years). No differences were found in personal or family history, sleep related breathing disorder (snoring, breathing pauses etc) and disturbed sleep. CONCLUSIONS: Occupational exposure to low concentrations of CO do not seem to affect ventilatory drive and the synchronisation of upper airway and respiratory muscles during sleep. It should be recognised that these results were obtained by a relatively insensitive technique (questionnaire); a protocol including polysomnography applied to subjects exposed to higher concentrations of CO could lead to other conclusions.

[Habitual snoring. Prevalence and risk factors in a sample of the French male population]. / Le ronflement habituel. Prévalence et facteurs de risque dans un échantillon de la population masculine française.

INTRODUCTION: As there are important differences in the prevalence of snoring in the literature we have studied this prevalence and the risk factors in a sample of the active male population of Lorraine. METHODS: 850 men, aged 22 to 66 tears, volunteered for the study and completed a questionnaire on the frequency of snoring, their lifestyle and their personal and family histories. The usual anthropomorphic measurements were made together with a non-invasive examination of the upper airways. RESULTS: The prevalence of habitual snoring was 34.6%, increasing with age, weight and the derived indices. We identified, by logistic regression, the factors independently associated with habitual snoring in univariate analysis. These were age, weight, nocturnal nasal obstruction, a medical diagnosis of obstructive sleep apnoea, and hypertrophy of the soft palate and uvula. There was evidence that height had a protective effect but exercise activity did not appear to be significant. CONCLUSION: The 35% prevalence of habitual snoring in our sample of middle aged men is similar to other studies in the literature using the same methods. The present study confirmed that age, weight, girth, nasal obstruction and nasopharyngeal abnormalities are risk factors. The protective effect of height was a new finding not identified in previous studies.

Determinants of accident proneness: a case-control study in railway workers.

BACKGROUND: Accident proneness or workers who have more frequent occupational injuries is common but the role of occupational and individual factors has rarely been studied. AIM: To assess the relationships of certain occupational and individual characteristics with frequency of occupational injuries. METHOD: This case-control study included 1305 male workers with occupational injuries during 1999-2000 and 1305 controls from a railway company. A standardized questionnaire was completed by the occupational physician in the presence of the subject. The data were analysed using logistic regression. RESULTS: Having more than one injury was associated with short service in the present job, younger age, sleep disorders, smoking, requesting a job change, physical disability and lack of physical activity. Safety training was negatively related to injury frequency. Short service in the present job was the only significant factor for single injuries. CONCLUSION: This study identified a number of work and individual factors that predicted occupational injury frequency and may be useful in designing preventative measures. Occupational physicians could assist workers to be more aware of the risks and to find remedial measures.

Witnessed breathing pauses during sleep: a study in middle-aged French males.

The aim of the study was to evaluate the prevalence, the covariates and determinants of respiratory pauses during sleep in a sample of French middle-aged males. Study subjects were 850 active males, aged 22-66 years; 88.4% of them answered the question on breathing pauses during sleep from a structured, validated sleep questionnaire. Forty-one (=5.4%) subjects reported breathing pauses at least once a week; these "positive responders" were older, heavier and had larger neck- and waist girths as compared to subjects with negative answers. Loud habitual snoring, various sleep disturbances, excessive daytime sleepiness, a doctor diagnosis of sleep apnoea, history of stroke and hypertension were significantly more frequent among subjects with breathing pauses during sleep. The prevalence found in this survey was close to that reported from the UK (5.2%). However, by logistic regression, we identified novel determinants of breathing pauses i.e. habitual snoring, loud snoring, and excessive sleepiness, factors well known in clinical setting, but never previously reported in epidemiologic studies.

Individual characteristics in occupational accidents due to imbalance: a case-control study of the employees of a railway company.

BACKGROUND: Falls are frequent occupational accidents, and are responsible for a significant amount of lost working time and, more importantly, for a high mortality. The factors involved in falling mechanisms can be of external or individual origin, the latter being less well identified. AIMS: To assess the relations between certain individual characteristics and occupational accidents due to imbalance. METHODS: A total of 427 male employees, who had been victims of at least one occupational accident with sick leave due to imbalance (cases) and 427 controls were recruited among the employees of a large French railway company. A standardised questionnaire on life conditions and professional factors, and a description of the accidents was filled in by an occupational physician for each subject. RESULTS: Some job categories were more affected by a specific release mechanism of work related falls. Certain individual characteristics such as smoking, alcohol consumption, inactivity, sleep disorders, and request for a job change were correlated with the occurrence of occupational accidents. Sick leaves of eight days or over were more frequent in older and overweight injured workers. Some lesions were linked with the specific fall released mechanisms. CONCLUSIONS: Individual characteristics can increase the risk of occupational accidents, especially falling. This study identified subjects most at risk on whom prevention related to working conditions and falls could be focused.

[School-related injuries: incidence, causes, and consequences]. / Les accidents scolaires dans des établissements d'enseignement général: incidence, causes, et conséquences.

BACKGROUND: School accidents are frequent but little epidemiological information is available to guide prevention. In this study we examined the incidence, causes, and consequences of school accidents as a function of the pupil's characteristics. METHODS: An epidemiological study was conducted in all 2 396 adolescents attending two secondary school groups. Sociodemographic characteristics of the pupils and data on school accidents during a one-year period were collected using a questionnaire filled out by the school nurse in the presence of the victims. The chi-square independence test, Fisher's exact test and the logistic regression method were used for the statistical analysis. RESULTS: Sports and physical training (SPT) accidents accounted for 52.8% of the accidents, recreation accidents for 12.7% and other accidents for 33.6%. The annual incidence of one accident or more, for all types of accidents combined, was 12.9%, that for two or more accidents 2.3%. The rate of SPT and recreation accidents decreased strongly with age. SPT accidents were more frequent in girls, the other accidents more frequent in boys. Among the SPT accidents, 69.2% occurred under training conditions and 33.7% were caused by another person. Causes mentioned by the victims were: carelessness (26.0%), clumsiness (17.5%), misappreciation of risk (13.8%), tiredness (9.5%), nervous irritation (8.6%), rowdyism (6.0%), disrespect of the teacher's instructions (6.0%). The lesions were: contusions (50.7%), wounds (18.7%), tendinitis (11.7%), wrenches (9.2%), others (7.3%). They differed between age groups, sex, and category of sports. Localizations were mainly: fingers (27.4%), other localizations of the upper limb (20.1%), head (20.6%). A physician was consulted for 19.5% of the accidents and hospitalization followed 2.7%. Absence from school and exemption from SPT were frequent (11.4% and 16.3% respectively). CONCLUSION: The results could be used to inform adolescents so they and their families could become more aware of the risk of school accidents. Prevention should mainly focus on the younger children. An effort must be made regarding risk assessment in order to help the pupils become more careful and responsible during their sports activities. The choice of these activities and the materials used should be made more suitable for adolescents.

Sick-building symptoms in office workers in northeastern France: a pilot study.

STUDY OBJECTIVES: To verify that sick building symptoms are present in north-eastern France office workers; to try to identify new confounding factors. METHODS: The design was that of a cross-sectional study with control group. We studied with the same methods the personnel of an air-conditioned building (n=425), and of a naturally ventilated building (n=351). Air temperature and humidity, bacterial and fungal densities were measured by the same technical staff in the two buildings. A standard questionnaire on irritative and respiratory symptoms, personal and family history, and lifestyle was completed by the participants. RESULTS: In univariate analysis, exposure to air-conditioning was associated with an increased prevalence of symptoms (odds ratios-OR-between 1.54 and 2.84). A significant increase in sickness absence was also found among subjects working in air-conditioned offices. As a series of factors were suspected to interfere with these associations, logistic regression was applied. This method confirmed exposure to be an independent determinant of 7 symptoms, and also identified two determinants not previously described: a family history of respiratory diseases and "do-it-yourself' activities. IN CONCLUSION: we found the sick building symptoms to be present in a group of French office workers exposed to air-conditioning. We confirmed the influence of a number of confounding factors and described two further confounders - do-it-yourself activities at home and a history of familial respiratory disease.

[Accidents among students in professional or technological schools in Lorraine]. / Les accidents chez les élèves des lycées professionnels et technologiques en Lorraine.

BACKGROUND: School accidents in adolescents in professional and technological secondary schools are relatively frequent. This work investigates these accidents in Lorraine (a French region) to identify preventive measures. METHODS: A cross-sectional study was carried out in 4,751 adolescents from five volunteering schools. Only accidents occurring during one school-year and declared to the Social Security Services as work accidents were studied. RESULTS: Incidence of accidents per 1,000 subjects was 52.0: 21.3 for accidents during sports and physical training (SPT), 7.8 for those occurring during school training (except SPT), and 22.9 for spare time accidents. The incidence increased strongly with age and differed greatly between the type of schools. Girls had more accidents during SPT than boys. Injuries during school training were wounds and contusions of upper limb while the injuries during SPT and spare time were mainly articular disorders, contusions, and wounds of the upper limb, the lower limb, and the head and neck. A physician was consulted in almost 100% of the injuries, a radiological examination was performed for 75%, and a surgical intervention for 14% of the injuries. Absence from school, exemption from workshops and from SPT were frequent. The predominant risk factors were the type of activities, especially activities the adolescents were not accustomed to, personal behavior and risks taken by adolescents. CONCLUSION: Accidents are frequent, in particular among older adolescents. It is important to identify activities at risk, and to target prevention and awareness campaigns, assessment training to evaluate risks of each activity, and promoting safe behavior, although environmental factors cannot be excluded.

Oral health in adolescents from a small French town.

In France, caries are more prevalent in rural areas than in large cities. This study analyzed the relationship between number of oral health indices and some known risk factors (toothbrushing, sugar consumption, saliva components) and sociodemographic factors in adolescents from a small town. The sample included 112 children aged 12-14 in the north-east of France. School marks was found to be better linked with dental caries indices than the socio-occupational category of parents: gingival index (GI), DMFS, DMFT and caries severity (CS) significantly increased with decreasing school marks; oral plaque was related to socio-occupational of parents. The analysis using the regression method showed that the variance explained by the various factors studied was modest (between 23 and 30%) for GI, initial caries sites (IS), DS, DMFS, DMFT and CS, and was small for plaque (5%) and calculus (3%). This would be due in part to the wide dispersion of these indices. The sex had a non-significant regression coefficient for all oral health indices investigated. For GI, only mutans streptococci (MS) and plaque had a significant regression coefficient. Calculus was explained by any factor considered. Only MS had a significant part in plaque. IS was explained by MS, toothbrushing and age. For DS, only toothbrushing, MS and sweet drinks during meals had a significant part. DMFS and DMFT were explained only by MS and age. CS was explained by MS, age, salivary buffer pH, salivary flow rate, and toothbrushing.

[Estimation of static lung volumes by nitrogen washout method. Single breath of oxygen]. / Estimation des volumes pulmonaires (statiques) par la méthode du rinçage d'azote. Inspiration unique d'oxygène.

Total lung capacity (TLC) and residual volume (RV) estimations were obtained from single-breath nitrogen washouts in 96 male and 77 female healthy never-smokers with normal spirometry from a non-polluted rural area in north-east France. TLC depended on height (both sexes) and diminished slightly with age in males, with the body-mass index (kg/m2) in females. RV increased with age in both sexes and with weight in males. The RV/TLC ratio was related only to age. When compared with values obtained using multiple-breath helium dilution, our results yielded lower predicted values. The test depends heavily on the subject's co-operation, and errors are frequent if a standard procedure is not observed. This method cannot thus be recommended for routine use in patients with respiratory diseases.

Standard descriptive tables in WHO Oral Health epidemiological studies.

For many years the Oral Health Programme of the World Health Organization has promoted the development of oral health epidemiological surveys. The objective of this article is to make oral health researchers aware of the variables and statistical tables recommended by WHO for the standardization, presentation and comparability of international surveys. The influence of the growing impact of computer technology in providing better knowledge of oral health systems is also discussed in this article.

Representation of affinity in the case of co-operativity in protein-ligand binding.

We have already proposed a "Global Association Function" to represent the global affinity of proteins to a drug; it was first applied in the case of independent binding sites. In this paper, we show that this same function can also be used to assess interactions between sites by varying the number of interacting sites and their co-operativity level. The resulting curves in two application cases are given together with the corresponding Scatchard plot: i) in a system with one single class of identical and interacting sites, ii) in a system with two classes of sites in which either primary or secondary are interacting; unexpectedly, in this latter case we also observed that sometimes positive co-operativity occasionally resulted in a concave-up Scatchard plot which is unusually admitted. In addition, as described in one example, our function is assumption free; this might be an advantage over usual methods, such as discrete parameter methods, because they require additional and empirical hypotheses on their related binding model.

Mortality of iron miners in Lorraine (France): relations between lung function and respiratory symptoms and subsequent mortality.

An increased mortality from lung and stomach cancer was found in previous studies on Lorraine iron miners. A detailed analysis, however, was not possible due to the lack of data for survivors. In this study the cohort included 1178 workers selected at random from all the 5300 working miners aged between 35 and 55 at the start of the follow up period, which ranged from 1975 to 1985. Occupational exposures and tobacco consumption, lung function tests, and respiratory symptoms were assessed for each subject in 1975, 1980, and 1985. This study confirmed the excess of lung cancer (standardised mortality ratio (SMR) = 389, p < 0.001) and of stomach cancer (SMR = 273, p < 0.05). There was no excess of lung cancer in non-smokers and moderate smokers (< 20 pack-years) or the miners who worked only at the surface or underground for less than 20 years. A significant excess (SMR = 349, p < 0.001) was found in moderate smokers when they worked underground for between 20 and 29 years. Heavy smokers (over 30 pack-years) or subjects who worked underground for more than 30 years experienced a high risk: SMR = 478 (p < 0.001) for moderate smokers who worked underground for over 30 years; 588 (p < 0.001) for heavy smokers who worked underground for between 20 and 29 years; and 877 (p < 0.001) for heavy smokers who worked underground for over 30 years. This showed an interaction between smoking and occupational exposure. The excess mortality from lung cancer was because there were some subjects who died young (from 45 years old). Comparison with the results of a previous study showed that additional hazards produced by diesel engines and explosives increased the mortality from lung cancer. The SMR was higher than 400 (p < 0.001) from 45 years old instead of from 56 years. A relation was found between a decrease in vital capacity (VC), forced expiratory volume in one second (FEV1) and of FEV1/VC and mortality from all causes and from lung cancer in heavy smokers or men who had worked underground for more than 20 years. Respiratory symptoms were related to mortality from lung cancer among smokers (moderate and heavy) who worked underground for more than 20 years. It is considered that the risk of lung cancer in the Lorraine iron miners was mainly due to dust, diesel engines, and explosives although the role of low exposure to radon daughters could not be totally excluded.

An analysis of the community periodontal index of treatment needs. Studies on adults in France. V. Presentation of CPITN data in cross-tabulations.

A total of 1005 subjects were examined using the CPITN and DFT indices. CPITN data were modified in their presentation in order to be suitable for cross-tabulation. Two different methods were considered. One, described previously by Roland et al. (1984), classified subjects according to the combination of their highest CPITN score and the mean of the highest scores of every nonedentulous sextant. The other consisted of multiplying the above mentioned mean by the individual's highest CPITN score. A critical analysis of the methodology showed that the two number system developed by Roland et al. (1984) was impractical. The new method provides a linear array of values from 0 to 16. Very little overlapping of values was observed, which means that a relatively precise periodontal condition is characterised by each value. With this transformation the CPITN can be used as an index that quantifies periodontal conditions instead of treatment needs.