GPS - Gute Praxis Sekundärdatenanalyse

The scientific use of secondary data, especially of claims data from health insurance funds, has continuously increased in the last years. Therefore the Working Group "Collection and Use of Secondary Data" (AGENS) of the German Society of Social Medicine and Prevention (DGSMP) took the initiative to define quality standards for secondary data analysis. Starting with a review of the Good Epidemiologic Practice (GEP) AGENS adapted the GEP to the specific requirements of secondary data analysis by a multi-stage consensus process. The guideline Good Practice Secondary Date Analysis (GPS) was adopted on January 15 (th), 2005. GPS consists of 10 guidelines which are divided in explaining comments and recommendations. The GPS are targeted to set up standards for secondary data analysis, and they may also be used as a foundation of contracts between data owners and scientists. They are addressed to scientists from health services research and social medicine. AGENS commits itself to revise GPS continuously.

[Changes in the quality of life after organ transplantations]

138 patients with end-stage kidney disease and 118 patients with end-stage liver disease were included in an observational cohort study regarding their quality of life. Instruments used were the Nottingham Health Profile (NHP), a scale for Activities of Daily Life (ADL), a Symptom Check List (SCL-90-R), and the Center of Epidemiology and Statistics Depression Scale (CES-D), all for self rating, as well as the indices of Spitzer and Karnofsky for foreign rating of life quality. Apart from the early postoperative period in both groups there was significant and persistent improvement in quality of life already three months after transplantation. In some dimensions, patients after kidney transplantation presented even lower trouble scores than a population sample. In addition, semistructured interviews showed clearly the need for psychotherapeutic support to guarantee the success for specific cases. The present investigation demonstrates, that systematic registration of the patients perception of illness and treatment is possible even in extreme situations and leads to a differentiated evaluation of medical procedures. Thereby the study also contributes to the development of modern evaluation research according to the spirit of evidence based medicine.

[Polyneuropathy and encephalopathy caused by organic solvents and mixed solvent solutions. Occupational medicine and neurologic aspects of a new occupational disease]

Solvent induced polyneuropathy and encephalopathy have been acknowledged quite recently as occupational diseases in Germany. For compensation first of all the diagnosis has to be proven. For differential diagnosis other known causes as well as non-organic mental diseases must be taken into consideration. The causality between proven exposures and diagnosed disease has at least to be probable. To evaluate causation extensive experience of the experts is needed. In this context scientific criteria regarding neurotoxicity of the solvent, duration of exposure, individual aspects of non-occupational influences, time course of the disease are important within a through synoptic evaluation. Possibilities and limitations of sensitive diagnostic measures such as neurographic, neuropsychologic and neuroimaging examinations are discussed. The prognosis of toxic polyneuropathy and encephalopathy is in general favorable if exposure has stopped. Additionally, adequate therapy and rehabilitation measures are supportive for a good prognosis.

[Determinants of the quality of life in chronic renal failure]

Dialysis patients, waiting for kidney transplantation, were asked about their quality of life. Data from 1027 persons have been collected. Compared to a population sample by the "Nottingham Health Profile" (NHP), dialysis patients showed double the frequency of symptoms--only for the subscale "pain" no significant difference could be recognised. Duration of dialysis treatment reduces the quality of life considerably: increasing troubles have been observed through different quality of life scales. Age shows less important influence concerning "pain" and "physical mobility", even a decrease of symptoms in elder patients has been demonstrated by NHP-subscales for "emotional reaction" and "social isolation". Gender, education, kind of disease and dialysis treatment, and the fact of former transplantations had only marginal influence on some different dimensions of life quality. The study demonstrates in which way the patients perception of life quality could be operational and integrated in analysis and evaluation of therapeutic procedures.

[Distal ulnar nerve irritation]

The authors present a rare compression syndrome of the deep branch of the ulnar nerve distally to the adductor pollicis muscle at the third metacarpal. After neurolysis, regeneration was proved clinically and electroneurographically.

[Neurotoxicity of chemical substances in the workplace. VI. Longitudinal study of persons occupationally exposed to mercury]

A longitudinal study was performed on eleven persons, who had been chronically exposed to mercury (Hg) (3 to 31 years, median 5 years) in 1977, 1980 resp., and 1982. During their work in a chemical plant they had had contact to elemental Hg and various inorganic as well as organic mercury compounds. The main purpose of the investigation was the evaluation of possible adverse effects to the nervous system caused by mercury. The internal Hg-exposure was measured by mercury analysis in blood (Hg-B) and in urine (Hg-U). Furthermore "time-weighted average" levels were calculated on the basis of former Hg-determinations from 1974 to 1982. For Hg-B these values ranged between 26 and 104 microgram/dl (median 42 microgram/l) and for Hg-U between 73 and 434 microgram/g creatinine (median 233 microgram/g creatinine) (upper normal levels: Hg-B: 5 microgram/l; Hg-U: 5 microgram/g creatinine). The determination of the peripheral nerve conduction velocities (NLG) of motor and sensory fibers as well as the registration of somatosensory-evoked potentials (SEP) revealed no pathological results, except one borderline case. The NLG- and SEP-values did not significantly differ from those of non exposed persons or from those of former NLG-determinations. No correlations were found between indicators of Hg-exposure and neurophysiological parameters regarding dose-effect-relationship. Statistical differences resulted in the time-dependent test of the psychological test battery performed in comparison to age-matched control persons of equal socio-economous status. In additional, significant relationships were calculated between Hg-exposure and these tests. Considering the inter- and intraindividual variations of the psychological test results, there were no substantial alterations in the total findings over the observed period except for one case. Workers with Hg-exposure below the current BAT-values (Hg-B 50 microgram/l, Hg-U 200 microgram/l) showed no pathological findings in the neurological, neurophysiological and neuropsychological examinations.

[Hemodynamic effect of carotid stenoses and longtime course following carotid surgery]

Between 1962 and 1980, a total of 706 patients with chronic arteriosclerotic vascular changes or kinking or coiling of the carotid artery, were subjected to surgery at the Surgical Department of the University Hospital at Erlangen. In 1981, a total of 703 patients were analysed to obtain information about the postoperative course. In addition to a computation of the survival rates, together with the stroke rates, broken down by the clinical stage, the preoperative haemodynamic effect of the carotid stenosis was taken into account. Patients with transient ischaemic attacks or mild cerebral infarction affecting the carotid artery territory, revealed a favourable long-term survival rate, and a low rate of strokes, irrespective of whether haemodynamically effective carotid stenoses presented or not. Patients with asymptomatic carotid artery stenosis, with chronic cerebral ischaemia, with non-hemispheric attacks, and with completed cerebral infarction, revealed, all in all, no favourable survival rates. For patients with preoperative haemodynamically effective carotid stenoses, the incidence of strokes was markedly lower than in patients without haemodynamically effective stenoses. This means that an indication for carotid artery surgery in these patients, can only be justified if the carotid stenosis is haemodynamically effective, but not if the stenosis is lowgrade.

[Somatosensory cortical stimulus response evoked potentials in unilateral symptoms caused by cerebrovascular disorders or brain tumors]

Comparative investigations of somatosensory evoked potentials in 23 patients with hemisyndromes following acute ischemia of the middle cerebral artery region and in 12 patients with similar hemisyndromes on the base of cerebral neoplasms revealed marked differences. Whereas in 87% of the patients with ischemic lesions the primary cortical complex of the SEP was severely altered there were similar abnormalities in only one of the patients with neoplasm. The SEP changes were not dependent on the neurologic (sensory) symptoms nor on focal or diffuse EEG abnormalities.

[Can the electroencephalogram contribute to the indications for carotid surgery?]

In a follow-up study (performed in 1981) of patients who underwent endarterectomy because of arteriosclerotic carotid artery stenosis or kinking between 1962 and 1980, those cases were analyzed which did not suffer carotid ischemic attacks but were either asymptomatic or had uncharacteristic symptoms (like dizziness or syncopal attacks) or brain stem symptoms indicating vertebro-basilar insufficiency. In all of these patients EEG recordings were performed before operation. From a total group of 324 patients 44 had abnormal EEG findings. In these cases the incidence of surgical complications was somewhat higher as was the incidence of mortality and of strokes. Particularly in hemodynamically effective stenosis, mortality in the later course was higher in cases with pathologic EEG. Although an abnormal EEG cannot be regarded as an absolute contraindication for carotid surgery, these cases should be submitted to a thorough internistic examination and the indication for surgery should be made carefully.

Incidence of abnormal EEG findings in patients with obstructions of the carotid artery and their prognostic value for the postoperative long-term course

Between 1972 and 1980, a total of 706 patients were operated on at the Surgical Department of the University Hospital at Erlangen for chronic arteriosclerotic lesions, or kinking or coiling of the carotid artery; an evaluable preoperative EEG was recorded in 515 patients. Patients with an abnormal EEG revealed an increased early mortality rate, and a greater incidence of strokes in the long term. In patients with "controversial' indications for surgery, i.e., patients with asymptomatic carotid bruit, chronic cerebral ischemia, or nonhemispheric attacks, a low-grade increase in early mortality, the incidence of deaths, and the incidence of strokes in the long term, were established. Although an abnormal EEG cannot, by and large, be considered an absolute contraindication to surgery, it should, nevertheless, be a reason for carrying out a thorough internistic examination of the patient and for critically considering the surgical indications.

[Transitory ischemic attacks. Results of surgical therapy]

Classical transient-ischemic attacks in patients with proven occlusive disease of the carotid arteries are an absolute indication to operate. Operative reconstruction leads to a significant reduction in the incidence of cerebral infarction when compared to conservative treatment with inhibitors of thrombocyte aggregation. The survival rate of carotid endarterectomy in this stage was 96% after 5 years and 60% after 7 years. The actual stroke rate during this observation period was 5.1%. Contralateral stenosis should be treated operatively in order to achieve further reduction in the rate of cerebral infarction.

[Doppler ultrasound sonography of the supratrochlear artery in temporal arteritis (author's transl)]

The risk of ocular involvement in temporal arteritis is difficult to assess in the individual case. Using Doppler ultrasound sonography a clearly reduced flow or arrest of flow in the supratrochlear artery of the amaurotic side could be demonstrated in three patients. Attempts to compress branches of the external carotid artery caused no change of flow behaviour. Doppler sonography thus permits assessment of involvement of orbital vessels. This indicates the risk of loss of vision.

[Late results in supraaortic reconstructions (author's transl)]

Since 1965 we have performed 602 reconstructions at the supraaortic branches, mainly at the carotid artery. Follow-up showed equally good long-term results in subclavian reconstructions by transthoracic and extrathoracic approach. The patency was 90% after 6 years. Mortality in carotid endarterectomy was 1.6%. According to the Life Table Method the survival rate was 57.6% after 5 years in stage I, 73.7% in stage II, and 66% in stage IV.

[Peripheral nerve injuries complicating extracranial vascular surgery (author's transl)]

Peripheral nerve injuries may complicate extracranial vascular surgery. Pareses of the recurrent and hypoglossal nerves are clinically important. The nervus laryngeus superior, the ramus marginalis mandibulae of the facial nerve and the brachial plexus may be involved. Horner's syndrom indicating damage of sympathetic fibers may also appear. Lesions of the glossopharyngeal, vagus and phrenic nerves are rather seldom.