You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
How to define coronary heart disease in register-based follow-up studies: experience from the Helsinki Heart Study.
Abstract 1:
Information on coronary heart disease ( CHD ) obtained from the Finnish Hospital Discharge and Cause-of-Death Registers was compared with that collected in the Helsinki Heart Study ( HHS ) during an 8.5-year follow-up . The purpose of the comparison was two-fold , firstly , to study the accuracy of registration of CHD and secondly , to find out what diagnostic codes to use for CHD in register-based follow-up studies . The HHS cases were used as the ' golden st and ard ' and the CHD deaths and definite nonfatal acute myocardial infa rct ions ( AMIs ) ( all diagnoses ) were taken from the registers to establish the sensitivity of the Hospital Discharge and Cause-of-Death Registers combined . The sensitivity was 0.84 during the period 1980 - 86 and 0.87 during 1987 - 90 , with the positive predictive values 0.94 and 0.92 respectively . The treatment effects seen in the HHS were compared with the effects that would have emerged , if register-based information only had been used with different definitions of CHD . Of the register-based calculations , the one with the definition ' all CHD deaths and hospitalizations with the ICD-8 code 410 ' came closest to the HHS result , with a 32 % reduction ( P=0.028 one-sided ) of CHD incidence , while the original HHS result was a 34 % reduction ( P=0.008 one sided ) . However , when comparing Kaplan-Meier plots of cumulative hazards of CHD , the plot with a wider definition of CHD ( ICD-8 and ICD-9 codes 410 - 414 ) came closest to the HHS experience , especially if revascularizations were included in the latter . Definite AMI as a single definition of CHD might thus not be sufficient when study ing CHD risk , instead , at least two parallel definitions of CHD should be used


Title 2:
Accuracy of hospital discharge data: five alcohol-related diseases.
Abstract 2:
Accuracy of  hospital discharge register data was studied by comparing 954 r and omly selected abstract s to the respective medical records . The average percentages of agreement were : date of birth 98 , date of admission 96 , date of discharge 94 , area of residence 93 , principal diagnosis 91 , disposition on discharge 89 , marital status 84 , third diagnosis 83 , second diagnosis 76 , social group 74 , occupation 60 , and source of admission 49 . Accuracy of items was not related to alcohol etiology . An analysis of variance indicated that the number of items in agreement varied by both diagnosis and type of hospital


Title 3:
Validation of stroke diagnosis in the National Hospital Discharge Register and the Register of Causes of Death in Finland
Abstract 3:
The validity of stroke diagnosis in the National Hospital Discharge Register and the Register of Causes of Death was examined among 546 middle-aged men in Finl and . The subjects were cases of cerebrovascular diseases of the Alpha-Tocopherol , Beta-Carotene Cancer Prevention Study and identified by record linkage to the registers . In all , 375 events with cerebrovascular disease as hospital discharge diagnosis and 218 events with cerebrovascular disease as the underlying cause of death were review ed using specific criteria modified from the classifications of the National Survey of Stroke and the WHO MONICA Study . For hospital stroke diagnoses , there was agreement on diagnosis for all strokes in 90 % , for subarachnoid hemorrhage in 79 % , intracerebral hemorrhage in 82 % , and cerebral infa rct ion in 90 % . The respective agreement rates for stroke as the underlying cause of death were 97 % , 95 % , 91 % , and 92 % . The data were insufficient for review in 1 % and 3 % of the stroke events , respectively . Age , observation year and trial supplementation with alpha-tocopherol or beta-carotene had no effect on validity . In conclusion , the validity of stroke diagnosis was good in registers of hospital diagnoses and causes of death justifying their use for endpoint assessment in epidemiological studies


Title 4:
Comparing properties of audit data and routinely collected register data in case of performance assessment of hip fracture treatment in Finland.
Abstract 4:
OBJECTIVES To compare prospect i ve audit data and secondary administrative register data in the production of performance assessment information in the case of hip fracture treatment , and to cross-vali date the quality of information . METHODS First , a conceptual model for the performance assessment of hip fracture treatment was defined . This model was then utilized in comparisons between the prospect i ve audit data  concerning 106 consecutive hip fracture patients from the Kuusankoski Regional Hospital and corresponding register data from the Finnish Health Care Register and the Causes of Death Register . We examined the completeness of registration of patients and also the accuracy and degree of completeness of the registered data . Observed differences were checked against the medical records . RESULTS Register data lack clinical detail , but outperform prospect i ve data in the recording of inpatient care history . Completeness of the register data is very good . The accuracy of easily measurable variables in the register is at least 95 % . The agreement between register and audit data was 86.3 % for detailed hip fracture diagnosis . Polyserial correlation between the functional dependency variables was 0.68 . CONCLUSIONS Register and audit data have certain limitations and problems , but both seem to be suitable for the performance assessment of hip fracture treatment . To improve the feasibility of the administrative register data , the voluntary input of additional hip fracture event data to the register should be made possible . St and ardized instructions that guide the use of available register classifications in a sensible way would improve the quality of data


Title 5:
Are adverse events after carotid endarterectomy reported comparable in different registries?
Abstract 5:
OBJECTIVES To assess the extent of discrepancies between different vascular registries , at various levels of validation , and to investigate whether such differences might alter the morbidity and mortality rates obtained from the gold st and ard data set for carotid endarterectomy ( CEA ) . METHODS All CEA operations in Helsinki University Central Hospital from 2000 - 2005 were retrieved from the local vascular registry ( HUSVASC ) and the Hospital Discharge Registry ( HILMO ) . Both registries were vali date d at different levels to form the final data set . Total and indication-specific perioperative morbidity and mortality rates were estimated from each level of validation and compared with those from the final data set and with pooled rates from systematic review s. RESULTS Initial search provided 675 and 681 CEAs from HUSVASC and HILMO , respectively , decreasing to 636 ( 94 % ) and 614 ( 90 % ) when using the specific operative codes for thrombendarterectomy and patch angioplasty . Manual verification of initial HUSVASC results proved that 655 ( 97 % ) operations were true CEAs . 18 further proven CEAs , registered only in HILMO , were added to form the final CEA data set ( n=673 ) . The peri-operative morbidity and combined morbidity and mortality rates were 2.23 % and 2.67 % , respectively . Comparable rates were obtained from both registries , irrespective the level of verification . CONCLUSION Registry data do not appear to be biased by r and om loss of some operations and thus they are reliable for decision-making . However , further research is still needed to estimate the permissible volume of omissions in a registry for the data -base to remain trustworthy
Conclusions : Completeness and accuracy in the register seem to vary from satisfactory to very good in the register as long as the recognised limitations are taking into account .