Practice variation in the odds of depressed elderly on multimorbidity and polypharmacy

general practitioner medication Depression,

F. Holvast
Prof. dr. P.F.M. Verhaak

Nature of the research:
Case control study on large database with morbidity and treatment figures of 1500 depressed elderly (age > 60) and matched (age/sex) controls

Fields of study:
GP medicine

Background / introduction
Depression at older age often coincides with other chronic morbidity.(1)( (2) (3, 4). The most frequently occurring combinations are depression together with hypertension, arthritis, diabetes, COPD/Asthma, stroke, cancer, heart failure or heart disease (4). This results in diagnostic and treatment problems in general and in problems with medication specifically.
Multi-morbidity goes together with poly-pharmacy. Calderon-Larranaga et al. identified seven patterns of poly-pharmacy, among which a depression-anxiety pattern, which is the most occurring pattern among men and women above 65 years. Within this pattern a wide range of drugs can be observed, among which, besides of course different kinds of psychopharmacological drugs, also drugs for peptic ulcer, laxatives, iron preparations, capillary stabilizing agents and cardiac glycosides (5).

In earlier analyses we found that depressed patients had a 16% (95% CI 10-24%) higher rate of chronic somatic diseases and had higher odds for multi-morbidity (OR 1.55; 95% CI 1.33-1.81) compared to mentally healthy controls. No difference existed between depressed patients and patients with other psychological diagnoses. Compared to mentally healthy controls, depressed patients had a 46% (95% CI 39-53%) higher rate of chronically used drugs and had higher odds for polypharmacy (OR 2.89; 95% CI 2.41-3.47). Comparable trends were found comparing depressed patients to patients with other psychological diagnoses (IRR 1.26; OR 1.75; both p<.001).

In our multilevel analyses we found a statistical significant part of the variance explained by the practice level. Therefore we intend to further analyze our data regarding a number of practice variables, available in our database: practice region, urbanization, years of experience of GP, gender of GP, in order to find practice characteristics related to the probability of depressed patients to have more multi-morbidity and polypharmacy.
Research question / problem definition
Which practice variables are related to the odds of depressed elderly on multimorbidity and polypharmacy ?
In order to determine the odds of depressed elderly on adherence as compared to non-depressed elderly, a case – control design including three groups (see below) will be followed.

Patients older than 60 years with a GP diagnosis of major depression (ICPC = P076) are matched with a control group of patients older than 60 years who presented with a psychological symptoms or disorder (but not major depression) in the past year and a matched control group of patients older than 60 year who did not present with any psychological symptom or disorder in the past year. The three groups are matched on age, gender and number of visits to the general practice. All these characteristics are available in the database

Available data
Data on 2012 have been retrieved from NIVEL Primary Care Database and the pharmaceutical database SFK. Within the NIVEL Primary Care Database, GPs in ± 200 family practices register and code all health problems presented within a consultation according to the International Classification of Primary Care (ICPC). Pharmacy dispensing data are collected nationwide in the Netherlands by the Foundation for Pharmaceutical Statistics (SFK). Data from both sources have been linked anonymously as has been done before (13). This linking is done by birthday, gender, geographical postcode and prescribed prescriptions. In a similar way, linking to the population registry of Statistics Netherlands is possible. For the 2011-2012 linking, this resulted in the combination of 122 pharmacies to 213 general practices.
From the NIVEL Primary Care Database we have information on:
• patients’ acute and chronic disorders (comorbidity)
• medicines prescribed by the GP, for each different disorder
• number of contacts/year
• adverse events with medication
• age, gender of the patient
Additionally information can be collected on
• practice size
• practice region (North, East, South, West)
• urbanization
• years of experience of GP
• gender of GP
From the pharmaceutical database SFK we get information on:
• patients who keep getting the medication, patients who start to get the medication but stop after one fill and patients who never get their medication

1512 patients, older than 60 years, with a diagnosis by the GP of major depression ICPC P76) in 2012 have been included, matched with 1497 patients with other psychological diagnoses and 1508 healthy controls .

Outcome measures
Multimorbidiy (defined as having two or more chronic conditions)
Polypharmacy (defined as using five or more medications chronically)
Drug Burden Index: a quantification of the cumulative anticholinergic and sedative drug load
The principal determinant is being depressed vs not being depressed (group 1 vs group 2 and 3), respectively having a psychological diagnosis during index year vs no psychological diagnosis (group1,2 vs group 3).
The second determinant are practice characteristics: size, region, urbanization, GP’s experience, GP’s gender

Data analysis

Multivariable multilevel logistic regression analyses will be performed with multimorbidity respectively polypharmacy as dependent variables and practice characteristics as determinants on the practice level.
Caughey GE, Roughead EE, Shakib S, McDermott RA, Vitry AI, Gilbert AL. Comorbidity of chronic disease and potential treatment conflicts in older people dispensed antidepressants. Age Ageing. 2010;39(4):488-94.
2. Iosifescu DV, Nierenberg AA, Alpert JE, Smith M, Bitran S, Dording C, et al. The impact of Medical Comorbidity on acute treatment in major depressive disorder. American Journal of Psychiatry. 2008;160:2122-7.
3. Nuyen J, Volkers AC, Verhaak PF, Schellevis FG, Groenewegen PP, Van den Bos GA. Accuracy of diagnosing depression in primary care: the impact of chronic somatic and psychiatric co-morbidity. Psychol Med. 2005;35(8):1185-95.
4. Sinnige J, Braspenning J, Schellevis F, Stirbu-Wagner I, Westert G, Korevaar J. The prevalence of disease clusters in older adults with multiple chronic diseases--a systematic literature review. PLoS One. 2013;8(11):e79641.
5. Calderon-Larranaga A, Gimeno-Feliu LA, Gonzalez-Rubio F, Poblador-Plou B, Lairla-San Jose M, Abad-Diez JM, et al. Polypharmacy Patterns: Unravelling Systematic Associations between Prescribed Medications. PLoS One. 2013;8(12):e84967.
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