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Utilizing national patient-register data to control for comorbidity in prognostic studies.

Nilssen Y, Strand TE, Wiik R, Bakken IJ, Yu XQ, O'Connell DL, Møller B - Clin Epidemiol (2014)

Bottom Line: When the PRI was added to the model including age and sex, the age effects were reduced by up to 38% for patients older than 50 years.All measures of model fit improved for the PRI model.Adjustment for comorbidity is especially important for patients 50 years of age or older, and its effect on 1-year mortality is almost comparable to the age effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Registration, Cancer Registry of Norway, Oslo, Norway.

ABSTRACT

Objective: To construct an updated comorbidity index (Patient Register Index [PRI]) using national data collections from Norway and compare its predictive ability of 1-year mortality with the Charlson Comorbidity Index (CCI).

Materials and methods: Data regarding over 1.11 million patients registered in the Norwegian Patient Register in 2010 and 2011 were used to construct the PRI. The PRI was evaluated by comparing its model fit and discrimination with the CCI.

Results: Compared with the CCI, the PRI weights decreased for six, increased for four, and were unchanged for seven diseases. When the PRI was added to the model including age and sex, the age effects were reduced by up to 38% for patients older than 50 years. All measures of model fit improved for the PRI model.

Conclusion: Adjustment for comorbidity is especially important for patients 50 years of age or older, and its effect on 1-year mortality is almost comparable to the age effect. The PRI is based on more recent data than the CCI, and is more representative of the general population due to its construction.

No MeSH data available.


Related in: MedlinePlus

Flowchart shows the included and excluded patients in the study population.
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f1-clep-6-395: Flowchart shows the included and excluded patients in the study population.

Mentions: To provide information on the total disease history of the patient, the personal identification number was used to link episodes of treatment registered at different hospitals, sectors, and years. Initially, all patients in the NPR registered with a hospital visit in 2010 or 2011 were identified, constituting 15,214,796 visits. Figure 1 shows an overview of exclusions of patient visits in the study. Three subgroups of the initial data suffered from incomplete reporting of personal identification numbers. The first group was outpatients at private specialist practices in 2010 and 2011 (3,359,618 visits). The reason for incomplete reporting in this group was mainly related to technical limitations in their information-technology systems. To avoid any selection bias, we then also excluded 10,131,791 outpatient visits registered at publicly financed hospitals. However, we decided to keep outpatient visits with surgical procedure codes, because this activity mainly is performed at publicly financed hospitals or publicly financed private hospitals. The second group of visits excluded due to incomplete reporting were data on newborn babies (139,196 visits), since a large proportion had not yet received a personal identification number at the time of registration. The third group was any other patient visits that were lacking a correctly reported personal identification number (49,249 visits). After these exclusions, the data were aggregated, resulting in 1,534,942 eligible visits, corresponding to 1,113,341 unique patients.


Utilizing national patient-register data to control for comorbidity in prognostic studies.

Nilssen Y, Strand TE, Wiik R, Bakken IJ, Yu XQ, O'Connell DL, Møller B - Clin Epidemiol (2014)

Flowchart shows the included and excluded patients in the study population.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4216019&req=5

f1-clep-6-395: Flowchart shows the included and excluded patients in the study population.
Mentions: To provide information on the total disease history of the patient, the personal identification number was used to link episodes of treatment registered at different hospitals, sectors, and years. Initially, all patients in the NPR registered with a hospital visit in 2010 or 2011 were identified, constituting 15,214,796 visits. Figure 1 shows an overview of exclusions of patient visits in the study. Three subgroups of the initial data suffered from incomplete reporting of personal identification numbers. The first group was outpatients at private specialist practices in 2010 and 2011 (3,359,618 visits). The reason for incomplete reporting in this group was mainly related to technical limitations in their information-technology systems. To avoid any selection bias, we then also excluded 10,131,791 outpatient visits registered at publicly financed hospitals. However, we decided to keep outpatient visits with surgical procedure codes, because this activity mainly is performed at publicly financed hospitals or publicly financed private hospitals. The second group of visits excluded due to incomplete reporting were data on newborn babies (139,196 visits), since a large proportion had not yet received a personal identification number at the time of registration. The third group was any other patient visits that were lacking a correctly reported personal identification number (49,249 visits). After these exclusions, the data were aggregated, resulting in 1,534,942 eligible visits, corresponding to 1,113,341 unique patients.

Bottom Line: When the PRI was added to the model including age and sex, the age effects were reduced by up to 38% for patients older than 50 years.All measures of model fit improved for the PRI model.Adjustment for comorbidity is especially important for patients 50 years of age or older, and its effect on 1-year mortality is almost comparable to the age effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Registration, Cancer Registry of Norway, Oslo, Norway.

ABSTRACT

Objective: To construct an updated comorbidity index (Patient Register Index [PRI]) using national data collections from Norway and compare its predictive ability of 1-year mortality with the Charlson Comorbidity Index (CCI).

Materials and methods: Data regarding over 1.11 million patients registered in the Norwegian Patient Register in 2010 and 2011 were used to construct the PRI. The PRI was evaluated by comparing its model fit and discrimination with the CCI.

Results: Compared with the CCI, the PRI weights decreased for six, increased for four, and were unchanged for seven diseases. When the PRI was added to the model including age and sex, the age effects were reduced by up to 38% for patients older than 50 years. All measures of model fit improved for the PRI model.

Conclusion: Adjustment for comorbidity is especially important for patients 50 years of age or older, and its effect on 1-year mortality is almost comparable to the age effect. The PRI is based on more recent data than the CCI, and is more representative of the general population due to its construction.

No MeSH data available.


Related in: MedlinePlus