Validity of self-reported diseases from health surveys: comparisons with registry data in Denmark

Background

The validity of self-reported disease prevalence estimates in health surveys may be low when compared to data from medical records in administrative registers. Such discrepancies reflect a low content validity of the survey question, which may ultimately compromise the application of these survey data for public health purposes. The aim of the present study was to examine the agreement of self-reports of seven diseases with data from administrative registers, both overall and by sociodemographic characteristics.

Methods

Prevalence estimates of self-reported current and/or previous diabetes, asthma, rheumatoid arthritis, osteoporosis, myocardial infarction, apoplexy, and cancer, respectively, were derived from the Danish National Health Survey in 2017 (n = 183,372 adults aged ≥16 years). Individual-level data were linked to registry data on the same diseases. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), kappa, and total agreement between self-reported and registry-documented prevalence estimates were examined.

Results

For all included diseases, the specificity was >92%, and the sensitivity varied between 59% (cancer) and 95% (diabetes). NPV was >94% for all diseases and PPV varied between 13% (rheumatoid arthritis) and 93% (cancer). Total agreement varied between 91 % (asthma) and 99% (diabetes), whereas kappa was lowest for rheumatoid arthritis (0.21) and highest for diabetes (0.88). Sociodemographic variables were significantly associated with total agreement with sex, age, and educational level exhibiting the strongest associations.

Conclusions

Overall, total agreement, specificity, and NPV between self-reported and registry-documented disease prevalence estimates are high, but PPV and kappa vary greatly between diseases. The latter findings reflect a low content validity of the applied survey question for specific diseases. This should be taken into account when interpreting similar results from surveys.

Key messages

• The validity of self-reported disease prevalence estimates may be low when compared to data from medical records. We found positive predictive values and kappa to vary greatly between diseases.

• Future studies should aim at designing survey questions properly in order to ensure a high content validity of the applied question.

Macrocephaly-cutis marmorata telangiectatica congenita syndrome--prenatal signs in ultrasonography

A new case of macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC) syndrome is described. The patient presented typical congenital findings in utero, although the syndrome was diagnosed postnatally. The M-CMTC syndrome should be considered when there is a marked fetal overgrowth and progressive macrocephaly with no indications of maternal hyperglycemia or fetal hyperinsulinism. Our patient also had unilateral pleural effusion, curved femur and frontal bossing.

Stent impact on the geometry of the carotid bifurcation and the course of the internal carotid artery

A measurement system is proposed to evaluate reconstructive effects of carotid stents on the geometry of the carotid bifurcation and the course of the internal carotid artery. To describe deviations of the stenotic internal carotid artery (ICA) from the extended axis of the common carotid artery (CCA) the CCA-ICA angle is measured between the CCA midaxis and the midaxis of the stenotic ICA segment. Maximal extensions of ICA tortuosities perpendicular to the course of the CCA axis are defined as ICA offset. The measurements were applied to DSA images of 224 carotid stenoses to evaluate variation and correlation between the two parameters. Comparative pre- and post-stent evaluation was performed in two series of 55 and 31 carotid stenoses treated with Wallstents and in a historic control group of 35 stenoses treated with Strecker stents. Straight course of the ICA was associated with low angle and low offset values, whereas tortuous course of the ICA showed larger angle and offset. A moderate linear correlation between the two parameters was found. Corresponding to a straightening of the stented segment, Wallstents reduced mean angle and offset values significantly. In five cases of the second series of Wallstents, transferrals of curves above the distal stent end associated with kinks were observed, and offset remained constant or increased. Strecker stent implantation caused no significant changes of bifurcational geometry. The proposed parameters corresponded to visual aspects of ICA tortuosity and detected reconstructive effects of self-expanding Wallstents on the ICA course. The measurement system may provide a basis for geometric evaluation of different stent types or implantation concepts with the aim: to optimize anatomic recanalization results in tortuous high angle-high offset bifurcations.

Detection of small for gestational age fetuses by the combination of clinical risk factors and ultrasonography

Clinical risk factors of fetal growth retardation and targeted ultrasound examinations were combined to detect small for gestational age (SGA) fetuses below the 10th percentile weight for age in 1122 unselected singleton pregnancies, in which the true gestational age was confirmed by ultrasonography at 18 weeks. The prevalence of SGA infants was 6.0% in this population. A risk group of 236 (21%) mothers was referred for an ultrasound examination of fetal growth by the midwives of maternity welfare centers on the basis of low symphysis-fundal height or five other major maternal risk factors (pregnancy associated hypertension, loss of weight gain, a previous SGA infant, pre-pregnancy weight below 50 kg, any smoking during pregnancy). The sensitivity and positive predictive value of the clinical part of the study were 83.6 and 23.7%, respectively. Fetal growth was assessed by measuring both biparietal diameter (BPD) and transverse abdominal diameter. In the clinically selected risk group, 83.9% of the SGA fetuses could be detected by this method using a cutoff level of -1 standard deviation (SD). The two-step screening combining clinical and ultrasonographic methods in the detection of SGA fetuses in general population showed a sensitivity of 70.1%, a specificity of 95.5%, a positive predictive value of 49.5%, and a negative predictive value of 98.1%. After ultrasound examination, the definitive risk group for SGA was 8.5% of the total material of 1122.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound screening for fetal urinary tract malformations: a prospective study in general population

Routine ultrasound examination at a first level ultrasound unit was performed on 4586 fetuses in general pregnant population at 18 and 34 weeks, to detect urinary tract malformations. Suspected renal abnormality was confirmed by postnatal investigations. Infants were followed up to 2-4 years to detect any renal malformations missed in screening. Urinary tract abnormalities were observed antenatally in 27 fetuses, eight cases at 18 weeks, and 19 cases at 34 weeks. An anteroposterior diameter of renal pelvis of 1 cm or more was the criterion for fetal hydronephrosis, which was the main ultrasound finding in 18 fetuses showing 24 hydronephrotic kidneys. In five cases, slight hydronephrosis disappeared spontaneously after birth, explaining the five 'false positive' cases of the study. Four children had renal abnormalities that were missed antenatally. The incidence of true urinary tract malformations detected by screening antenatally was 0.48%, and the overall incidence after 2-4 years follow-up was 0.57%, which is much higher than reported earlier in series without routine ultrasound screening. The antenatal screening showed a sensitivity of 84.6%, a specificity of 99.9%, a positive predictive value of 81.5%, and a negative predictive value of 99.9%. The main differential diagnostic problems occurred in two fields: in differentiating (1) functional hydronephrosis from obstructive uropathy, and (2) multicystic renal dysplasia of Potter's type IV from severe hydronephrosis. The prenatal diagnosis in cases with definitive renal abnormality corresponded to the postnatal diagnosis in 19/22 (86.4%) of the cases. 68% of the infants with urinary tract anomaly survived, 60% of them undergoing postnatal surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative relationships between pain intensities during labor and beta-endorphin and cortisol concentrations in plasma. Decline of the hormone concentrations in the early postpartum period

In 38 women with uncomplicated vaginal delivery at term, the different pain intensities during spontaneous labor were correlated to the plasma beta-endorphin and cortisol concentrations simultaneously examined. The pain intensities subjectively assessed were numerically categorized. The women in labor categorized to pain intensities 0 to III were in comparable stages of cervical dilatation. The hormone concentrations were measured by means of radioimmunoassay. The lowest hormone levels were found after abolition of pains of labor by epidural anesthesia: beta-endorphin 42 pg/ml, cortisol 318 ng/ml (mean values). The hormone concentrations rose progressively with increasing intensities of labor pain. The highest concentrations were observed in the first few minutes after delivery i.e. immediately after cessation of the extreme pains of expulsive labor: beta-endorphin 118 pg/ml, cortisol 449 ng/ml. Statistically significant, positive correlations were calculated between beta-endorphin and cortisol concentrations in plasma and the self-reported pain intensities (p less than 0.001 and p less than 0.01 resp.). Thus, highly elevated beta-endorphin levels in plasma do not abolish pain, probably they modulate it. Within the first four hours postpartum the concentrations of the two stress-stimulated hormones dropped rapidly. The endorphin level fell from 118 pg/ml immediately after delivery to 38 pg/ml in the above mentioned period, the cortisol level from 449 ng/ml to 302 ng/ml. One to three days after delivery the beta-endorphin and cortisol concentrations in maternal plasma were largely normalized, this means they then approximately corresponded to the values being found in nonpregnant women under normal conditions.

Antenatal detection of congenital malformations by routine ultrasonography

Routine ultrasound examination was performed in 9012 fetuses of a general pregnant population to detect fetal malformations. The examination was done on 3098 fetuses at 18 weeks, and on 5914 fetuses it was repeated at 34 weeks. Ninety-three infants (1.03%) showed 123 major malformations, of which 65 (52.8%) in 54 children were visualized in utero. The sensitivity of detection of malformed fetuses was 58.1% (54 of 93), specificity 99.9%, positive predictive value 91.5%, and negative predictive value 99.6%. Five fetal hydronephroses were the only false-positive cases (0.06%), with apparent spontaneous resolution after birth. Fetal growth retardation, polyhydramnios, or oligohydramnios was observed in 43% of the malformed cases, suggesting the importance of these conditions in ultrasound screening. Abnormality of pregnancy was suspected clinically in only 25.8% of the cases at the time of diagnosis of fetal malformation, emphasizing the necessity for ultrasound examination of all pregnancies.

Myoglobin in third trimester amniotic fluid of human pregnancy--a potential indicator of fetal hypoxia

195 amniotic fluid samples from the third trimester were examined for their content of myoglobin by means of radio-immunoassay. 151 of the samples were obtained intrapartum, the rest (44) was taken antepartum by transabdominal amniocentesis within one week prior to delivery. Depending on the myoglobin levels measured, different amniotic fluid groups were defined: (A) amniotic fluids containing no myoglobin or traces of it (less than 3 ng/ml), (B) amniotic fluids with moderately elevated myoglobin levels (3-10 ng/ml), (C) amniotic fluids with high myoglobin levels (greater than 10 ng/ml). Myoglobin levels above 3 ng/ml could be measured in 98 of the 151 samples taken intrapartum. In the amniotic fluids drawn antepartum the proportion of "myoglobin-positive" samples (greater than 3 ng/ml) amounted to only 22.7% (10 out of 44 samples). In pregnancies with amniotic fluids showing high myoglobin levels intrapartum, the prevalence of meconium staining of the samples, pathological cardiotocograms intrapartum and metabolic acidoses in umbilical artery blood samples was significantly higher than in pregnancies with myoglobin-negative amniotic fluids. The frequency of cesarean sections for fetal distress rose with increasing myoglobin levels in amniotic fluid, being 5.7, 13, and 18.2% in Group A, B and C respectively. In the pregnancies in which the amniotic fluid samples were taken antepartum, the prevalence of meconium-stained amniotic fluid increased with elevating amniotic fluid myoglobin (p less than 0.05, Group A vs. Group C). The frequency of cesarean sections for fetal distress and of neonatal depression immediately after delivery was considerably heightened in the cases with myoglobin-positive amniotic fluids antepartum compared to those with myoglobin-negative liquor.(ABSTRACT TRUNCATED AT 250 WORDS)

Routine ultrasound screening for early detection of small for gestational age fetuses

A real-time ultrasound screening examination was performed in 3208 unselected singleton pregnancies at 18 and 34 weeks to detect small for gestational age (SGA) fetuses below the tenth percentile weight for age. Such cases accounted for 4.9% of this population. Biparietal diameter (BPD) was used at the first examination to confirm the true gestational age. The growth was measured at 34 weeks with a combination of BPD and transverse abdominal diameter. With a cutoff level of -1.5 standard deviations (SD), the sensitivity of a single measurement was 62.2%, the specificity was 93.2%, and the positive predictive value was 32.4%. With a cutoff level of -1 SD, the values were 76.3, 84.8, and 20.4%, respectively. The positive predictive value approached 48.7% before birth in the group that was rescanned before delivery. The simple method of a combined measurement of BPD and transverse abdominal diameter provided efficient antenatal screening for diagnosis of SGA fetuses in the general population. A somewhat low positive predictive value indicates a control examination of fetuses suspected of being SGA. Nonlinear methods, such as the measurement of abdominal circumference, appear suitable for ruling out false-positive cases.

Oral hygiene instruction in general dental practice by means of self-teaching manuals

The present study evaluates the applicability of delivering oral hygiene instruction to patients in general dental practice by means of self-educational programs. Patients (55) seeking dental treatment in 3 general dental practices in Denmark were divided at random into a conventional professional instruction group (C) in which each individual received personal instruction by the dentist and a self-instruction group (S), in which the patients were given self-educational programs. In order to evaluate the effect of the 2 types of instruction, the presence or absence of dento-gingival plaque and gingival bleeding by probing was recorded prior to the instruction and after 3 and 6 months. The patient of the self-instruction group (S) answered a questionnaire about the treatment 1 week after they had received the self-instruction program. An identical improvement in oral hygiene and gingival health was recorded in both treatment groups after 3 and 6 months. This finding indicates, that the self-educational programs were as effective in changing the oral hygiene habits of the patients as was personal oral hygiene instruction by dental personnel. The answers of the patients to the post-treatment questionnaire reflected a favorable attitude towards the use of self-educational programs.

[Statistical studies on caries in handicapped children]

The prevalence of caries in 108 mentally and physically handicapped children between the ages of 6 and 16 was determined in a clinical study. The prevalence of caries in residual teeth was extremely high, 100% higher than in the healthy control group. Caries-free dentition was not observed. The oral hygiene was totally inadequate in 94% of the children examined. The state of dental care for these patients was unsatisfactory. It was shown that directed prophylaxis is a necessity with handicapped children.