Early Detection of Primary Antibody Deficiencies in Primary Care Facilities by an Algorithm Driven Selection of Serologic Testing in Individuals at Risk.

Study Overview
=================
Brief Summary
-----------------
Rationale: Primary antibody deficiencies (PAD) encompass a group of rare heterogeneous diseases. The clinical presentation may vary widely, including infectious and autoimmune symptoms and increased risk of malignancy. Due to the rarity of the diseases and this wide array of symptoms there is often a delay in diagnosis, of up to 12 years on average1-4. Timely diagnosis of PAD reduces morbidity, mortality and health care costs as effective therapies are available. The currently available screening systems for the broader group of primary immunodeficiencies (PID) have been shown to have poor diagnostic performance5-10 and are time consuming. We have thus developed an algorithm to screen patient records in a primary care setting for risk factors specifically for PAD. Patients with a high risk may undergo a laboratory assessment and referral if necessary, thus reducing the diagnostic delay of PAD. The aim of the current study is to validate this algorithm. Objective: Main objective: to validate a screening algorithm for PAD in a primary care setting in the Netherlands. Study design: Mono-centre cohort study based on regular care data Study population: Primary care patients aged 12-70 years with the 100 highest scores based on our algorithm.

Official Title
-----------------
Early Detection of Primary Antibody Deficiencies in Primary Care Facilities by an Algorithm Driven Selection of Serologic Testing in Individuals at Risk.

Conditions
-----------------
Primary Antibody Deficiencies

Intervention / Treatment
-----------------
* Procedure: Blood withdrawal


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Age between 12 and 70 years A total algorithm score that is within the highest 0.66% of the algorithm scores within a single general practitioner's clinic Signed informed consent Did not meet exclusion criteria during manual evaluation of the health care record Exclusion Criteria: Secondary causes of immunodeficiency as registered by ICPC codes for: multiple myeloma, HIV-infection, anorexia nervosa, bulimia, cystic fibrosis. The presence of one of the following during manual screening of the health care record: nephrotic syndrome, current systemic chemotherapy and stage 3-4 liver cirrhosis will be excluded. This could not be done by the algorithm as there is no ICPC code available.

Ages Eligible for Study
-----------------
Minimum Age: 12 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Intervention/Treatment |
| --- |
|Procedure: Blood withdrawal|Single blood withdrawal for determination of immunoglobulin levels|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The percentage of high-risk patients with an eventual PAD diagnosis |  | measurement december 2022 |